Step-by-step explanation:
The above variation is written as
y = kx²
where k is the constant of variation
when y = 20 and x = 1
we have
20 = k(1)²
k = 20
So the formula for the variation is
y = 20x²
a).
when x is doubled that's x = 2
y = 20(2)²
y = 20(4)
y = 80
b).
when y = 80
We have
80 = 20x
Divide both sides by 20
x = 4
Hope this helps you
