Answer:
Step-by-step explanation:

(f+g)(x)=0
f (x) + g (x)=0
now,
substitute their values
x^2 -4x + x -18 = 0
x^2 -3x -18 =0
x^2 - 6x + 3x - 18 =0
x (x-6) + 3 (x-6) = 0
(x-6)(x+3) = 0
we have to find it's zeroes (or roots) now:
x-6 =0
x = 6
x +3 =0
x = -3
Calleigh should put in 30 pennies
3-5y= 2x
-5y= 2x-3
y= (-2/5)x + 3/5
y + 2 = (-2/5)(x + 3)
y + 2 = (-2/5)x - (6/5)
y + 10/5 = (-2/5)x - 6/5
y = (-2/5)x - 16/5 is the answer