Answer:
f(x) = - x + 20
Step-by-step explanation:
Start with x =0
that means that f(0) = 20
So
y = f(x)
y = ax + 20 Now if x = 1 , y = 18
18 = a(2) + 20 Subtract 20
18 - 20 = 2a combine
- 2 = 2a Switch
2a = - 2 Divide by 2
a = -2/2 Combine
a = - 1
y = - x + 20 Answer or
f(x) = -x + 20 Answer
