Answer:
b. $30
Step-by-step explanation:
producer surplus = price producer able to sell - price producer would be willing to sell
⇔ price producer able to sell = producer surplus + price producer would be willing to sell = 53 + (10+12+15) = $90 for 3 lawn
if Ronnie charges all customers the same price for lawn mowing, that price is $30 (= $90/3)