Answer:
a) C(x) = 4x + 350
b) 13x; $13
c) 39
Step-by-step explanation:
a) Initial cost of lawnmower = $350
Maintenance cost for 1 lawn = $4
Maintenance cost for x lawns = 4x
Total cost function, C(x) = 4x + 350
b) Revenue = Cost + Profit
= C(x) + P(x)
= 4x + 350 + 9x - 350
= 13x
Charge per lawn = 
= 
c) For Jimmy to make a profit, P(x) must be greater than zero i.e.



The smallest integer value of x that satisfies this inequality is 39. Therefore, Jimmy needs to mow 39 lawns in order to start making profit.