Variable y varies directly with x^2, and y = 75 when x = 5. What is the value of y when x = 3?

y I proportional to x^2
y = k x^2
k = y/x^2
k = 75 / 5^2
k = 75/25
k = 3 ( The constant of proportionality).

Hence
y = 3x^2
When x = 3
y = 3(3)^2
y = 3(9)
y = 27

y varies directly with x^2

y= kx^2 , where k is any constant
y=75; x=5

75 = k (5)^2
75 = 25 k
k = 3

y = 3x^2

when x=3:
y = 3 (3)^2
y = (3)(9)
y = 27