Y is 5 when x is 2.5, and y varies directly with x ... Find y when x is 10 ... 5. 7.5. 12.5. 20

Most of the information's required for solving this problem is already given in the question. Let us write them down first and then concentrate on the problem in hand.

When y = 5, then x = 2.5

So

y = kx

5 = 2.5k

k = 2

Now, when x = 10, then

y = kx

= 2 * 10

= 20

From the above deduction, we can conclude that the correct option among all the options that are given in the question is the last option.