The cost of 3 pens and 12 notebooks is ₹195. The cost of 7 notebooks exceeds the cost of 4 pens by ₹39. What is the cost of 12 pens and 6 notebooks?​

Correct option is C

Given:

Cost of 3 pens and 12 notebooks = ₹195

Cost of 7 notebooks exceeds cost of 4 pens by ₹39

Solution:

Let the cost of one pen = ₹x

Let the cost of one notebook = ₹y

So,

3x + 12y = 195 …(1)

7y = 4x + 39 => 7y - 4x = 39 …(2)

From (2):

7y - 4x = 39

Multiply (1) by 4 and (2) by 3 to eliminate x:

(1) × 4 => 12x + 48y = 780

(2) × 3 => 21y - 12x = 117

Now add both:

(12x + 48y) + (−12x + 21y) = 780 + 117

=> 69y = 897

=> y = ₹13

Substitute y = 13 in (1):

3x + 12×13 = 195

3x + 156 = 195

3x = 39

x = ₹13

Now, cost of 12 pens and 6 notebooks = 12x + 6y

= 12×13 + 6×13 = 156 + 78 = ₹234