Answer:
28 bicycles
Step-by-step explanation:
In one week he will earn $120. This is guaranteed if he goes to work and is therefore the constant.
let x be the number of bicycles sold
P(x) = 10x + 120
400 = 10x + 120
280 = 10x
x = 28
He needs to sell 28 bicycles to earn $400 each week. He needs to sell ≥28 bicycles.