If y is inversely proportional to x^2...
y=k/x^2, we are given that y=2.5 and x=24 so
2.5=k/24^2
k=2.5(24^2)
k=1440 so
y=1440/x^2
y(20)=1440/400=3.6 so y=3.6 when x=20
x^2=1440/y
x^2=1440/16
x^2=90
x=±√90
x=±3√10
approx...
x=-9.49 and +9.49 so there are two possible values for x when y=16
