Answer:
a) x = -270
b) y = 304/9 or y = 33.78
c) x = -37.8
Step-by-step explanation:
y varies directly with x so y = kx
a)
y = kx
k = y/x
k = 10/-30 = -1/3
So
y = -1/3 x
If y = 90 then
90 = -1/3 x
x = 90 *(-3) = -270
b)
k = y/x
k = -19/-4.5
k = 38/9
So
y = 38/9 x
If x = - 8 then
y = 38/9 *(-8)
y = 304/9 or y = 33.78
c)
k = y/x
k = -4.3 / 12.9
k = - 1/3
So
y = -1/3 x
If y = 12.6 then
12.6 = -1/3 x
x = 12.6 *(-3)
x = -37.8
