Problem: Sanjay will be 3 times as old as he was 4 years ago after 18 years. Find his present age?

Solution:

Let Sanjay's present age be x years.

After 18 years, Sanjay's age will be (x + 18) years.

Four years ago, Sanjay's age was (x - 4) years.

According to the problem statement, (x + 18) = 3(x - 4)

Solving the above equation, we get:

x + 18 = 3x - 12

2x = 30

x = 15

Therefore, Sanjay's present age is 15 years.

Explanation:

To solve the problem, we need to use algebraic equations and solve them to determine Sanjay's present age. We can start by assuming Sanjay's present age to be x years, and then use the information given in the problem statement to form an equation.

We know that Sanjay will be 3 times as old as he was 4 years ago after 18 years. This means that his age after 18 years will be three times his age 4 years ago. We can use this information to form an equation:

(x + 18) = 3(x - 4)

Solving the above equation, we get:

x + 18 = 3x - 12

2x = 30

x = 15

Therefore, Sanjay's present age is 15 years.

Conclusion:

Sanjay's present age is 15 years. We solved the problem by using algebraic equations and solving them to determine Sanjay's age. The key to solving the problem was to use the information given in the problem statement to form an equation and then solve it to find the answer.

Let Sanjay's present age be x
(x-4)3=x+18
3x-12=x+18
3x-x=18+12
2x=30
x=30/2
x=15
Check
(15-4)3=15+18
33=33