3 bags and 6 pens together cost ₹744, whereas 9 bags and 9 pens together cost ₹1,854. The cost of 6 bags exceeds the cost of 10 pens by:​

Correct option is C

Given:

Cost of 3 bags and 6 pens = ₹744

Cost of 9 bags and 9 pens = ₹1,854

Solution:

Let cost of 1 bag = ₹x, cost of 1 pen = ₹y

Then,

3x + 6y = 744.........(1)

9x + 9y = 1854.......(2)

Subtracting 3$$\times$$​ (1) - (2):

​$$9x + 18y = 2232\\ \underline{-9x \pm 9y = -1854}\\ \quad \quad 9y = 378 \\ \implies y = 42$$​​

Now, y = 42 in the equation (1) 

x = 164 

Cost of 6 bags = 6 × 164 = 984

Cost of 10 pens = 10 × 42 = 420

Difference = 984 - 420 = ₹564