If y varies inversely as x and x is 6 when y is 13, what is x when y is 8?

Question

If y varies inversely as x and x is 6 when y is 13, what is x when y is 8?

Answer 1

c= a constant, and y=c/x or xy=c.

xy= 6*13=88

x(8)=88

x=11, 

This makes perfect sense.  As y decreases x increases necessarily.

Answer 2

Inverse relation means that xy is constant.
We are given that x = 6 when y = 13 so xy = 6*13 = 78.
Thus to find x when y = 8, just plug in y in the equation to get:

8x = 78

x = 78/8 = 9.75