Question

Im helpless i dont get this at all.

Answer 1

a)
y varies directly as x, that means y α x

y = kx, where k = constant of proportionality.

y = kx, recall y = 9, x= 18

y = kx

9 = k*18

18k =9

k = 9/18 = 0.5

y = kx, substitute k = 0.5

y = 0.5x

b)

x = 5, y = ?

y = 0.5x

y = 0.5*5

y = 2.5

Hope this helps.

Answer 2

I assume that y = 1/2 of whatever x is, so in this case y = 2.5 because 5 (which is x) divided by 2 is 2.5

Hope this helps!