Question

Y and x have a proportional relationship, and y = 25 when x = 60. What is the value of x when y = 30?

Answer 1

The equation governiong this relationship is y = kx.  Since y = 25 when x = 60,
25 = 60k, and k=(5/12).  Thus, the equation is   y = (5/12)x.

If y = 30, then 30 = (5/12)x.  Mult. both sides by 12/5 to obtain the value of x:

(12/5)(30) = 360/5 = 72