An essential content area for the Quantitative section of the GMAT:
Why should you know GMAT algebra:
1. Approximately 15 algebra questions appear on the GMAT (and algebra skills tend to be useful on other types of questions as well).
2. Basic algebra on the GMAT is math that most test takers learned at age 1314, so the knowledge is probably still there, but most students are “rusty” and need to refamiliarize themselves with the concepts.
1V1E – 1 variable, 1 equation: I can solve it.
Questions with just 1 variable tend to be straightforward math questions that count! Solve with basic algebra and arithmetic skills.
Be sure that you:
1. Write EVERYTHING DOWN (including when you translate sentences into math formulas).
2. Combine “like” terms.
3. Simplify expressions (reduce fractions, etc).
Example:
A museum plans to triple its collection of painting. After doing so, there will be a total of 426 paintings. How many paintings does the museum currently have?
A. 132
B. 138
C. 142
D. 146
E. 152
“In terms of” questions will usually include those 3 words. While they will appear to be TEST IT questions, they’re usually best solved with standard math approaches. They will ask you to solve for a variable (for example, “what is x in terms of y?”).
Example:
If y = 3y+6/3x then what is x in terms of y?
(A) y+2/y
(B) y/y+2
(C) y+2/2y
(D) 2y/y+2
(E) y/2
Systems
“System” questions involve questions that have 2 or more variables and 2 or more equations for you to use. They’re traditional math questions (although they can sometimes be solved with TEST THE ANSWERS).
There are 2 math approaches to these types of questions: Substitution and Combination. On most System questions, the combination method is faster. Be on the lookout to use the substitution method though; in subtle questions, it’s actually the faster method.
2V2E – 2 Variables, 2 Equations…I can solve it!
The 2V2E is the standard in “System” questions. These questions usually appear as story problems and are worth points.
Example:
A class of boys and girls sells tickets for a school rafﬂe. Each boy sells 2 tickets and each girl sells 3 tickets. If 52 total boys and girls were involved and a total of 118 tickets were sold, then how many more boys than girls were involved in the rafﬂe?
(A) 6
(B) 14
(C) 18
(D) 20
(E) 24
2V2E – Trap
Make sure the two equations are truly two DIFFERENT equations.
Example:
what is the value of 7A  3B?
1) 14A  6B = 9
2) 7A + 3B = 4
2V2E – Time Shift
When a question involves a shift in time, that shift must apply to each character in the question.
Example:
Alan is currently 15 Years older than Ben. In 4 Years, Alan will be exactly twice Ben`s age. How old is Alan now?
(A) 11
(b) 19
(c) 23
(D) 26
(E) 37
Hint: In 4 Years: (A+4) = 2(B+4)
3V3E – 3 Variables, 3 Equations…I can solve it!
The 3V3E is a much rarer question type (so you might not see one). These questions can be solved with a LENGTHY series of calculations. However, there is usually a pattern (often involving the speciﬁc question that is asked) that can help you to answer the question in a much faster way.
Example:
Bob, Glen and Ed weigh a total of 280 pounds. If 4 times Bob's weight is equal to 660 pounds minus 4 times Ed's weight and Glen's weight is 70 pounds more than half of Ed's weight, then what is twice Glen's weight')
(A) 115
(B) 170
(C) 230
(D) 235
(E) 290
3V2E – 3 Variables, 2 Equations… I can still solve it!
The 3V2E is also a much rarer question type (so you might not see one). These questions can be solved with a LENGTHY series of calculations. However, there is usually a pattern (often involving the speciﬁc question that is asked) that can help you to answer the question in a much faster way.
Example:
Three photographers, Lisa, Mike and Norm, take photos of a wedding. The total of Lisa and Mike's photos is 50 less than the sum of Mike and Norm's photos. If Norm's total photos is 10 more than twice the number of Lisa's photos, then how many photos did Norm take?
(A) 40
(B) 50
(C) 60
(D) 80
(E) 90
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