Problem:
If the cost of 7 pencils is RS 8 more than the cost of 5 pencils, then find the cost of 14 pencils.

Solution:
To find the cost of 14 pencils, we first need to determine the cost of 1 pencil. From the given information, we know that the cost of 7 pencils is RS 8 more than the cost of 5 pencils. Let's represent the cost of 5 pencils as x.

Step 1: Define the variables
Let's define the variables:
Cost of 5 pencils = x
Cost of 7 pencils = x + RS 8
Cost of 1 pencil = ?

Step 2: Find the cost of 1 pencil
To find the cost of 1 pencil, we can set up a proportion. We know that the cost of 7 pencils is RS 8 more than the cost of 5 pencils, so we can write the following equation:

7 pencils / 5 pencils = (x + RS 8) / x

Simplifying the equation, we get:

7/5 = (x + RS 8) / x

Cross-multiplying, we have:

7x = 5(x + RS 8)

Expanding the equation, we get:

7x = 5x + 40

Subtracting 5x from both sides, we get:

2x = 40

Dividing both sides by 2, we get:

x = 20

Therefore, the cost of 1 pencil is RS 20.

Step 3: Find the cost of 14 pencils
Now that we know the cost of 1 pencil is RS 20, we can find the cost of 14 pencils by multiplying the cost of 1 pencil by 14:

Cost of 14 pencils = RS 20 * 14 = RS 280

Therefore, the cost of 14 pencils is RS 280.

Let the cost of pencils = ×
Cost of 7 pencils = 7×
Rs.8 more than 5 pencils = Rs.8+5×

According to question:
=>7× = Rs. 8+5×

=>7×-5×=Rs.8

=>2×=Rs. 8

=>×=Rs. 8/2

=>×Rs. 4

cost of 14 pencils=14×=Rs. 4*14=Rs. 56