Columns 1 through 3 in the table below show the marginal utility which a particular consumer would get by purchasing various quantities of products A, B, and C

for calculating, this first we have to find the per rupee utility of each product at each level, and on doing so we will see that the per rupee utility of product B is highest for all seven units of product being:

1st unit's utility 13

2nd unit's utility 12

3rd unit's utility 11

4th unit's utility 10

5th unit's utility 9

6th unit's utility 8

7th unit's utility 7 (Formula = utility/per unit cost)

So, seven units of product B must be purchased.

Remaining amount of rupees = $(26 - 7*3) = $5

Now we see the marginal utility per rupee is maximum for product C.

So 5 units of product C must be purchased.

Thus, in order to maximize the utility 7 units of product B and 5 units of product C must be purchased