math question: ?

right about 139.5 pizzas for a break-even point... considering you only wanted the answer ... but actually given the COST formula the company loses money after the first one [plug and chug for 2 pizzas] (or the impossible - the cost of producing the pizzas is less than zero.  C(10) = 10 - 150 + 15 = -$125 cost vs $60 in sales). YOUR FORMULA IS WRONG / MISSTATED - ACCOUNTANT

 A pizza shop is having a special, for one week all large pizzas will only cost consumers $6.00. If the cost to the shop to produce the pizzas is represented by the function C(x) = 10 - 15x + 0.15x^2, how many pizzas can the shop sell before they begin to lose money?

Cost, C(x) = 10 - 15x + 0.15x²
Revenue, R(x) = 6x
For Loss, C(x) > R(x)
10 - 15x + 0.15x² > 6x
10 - 21x + 0.15x² > 0
x = {-(-21)±√[(-21)² - 4(0.15)(10)]} / (2*0.15)
x = (21±√435)/0.3
x = 0.5 and 140 

So at 1st pizza will be in loss but then the shop will make profit until the 140th pizza. After which the shop will be in loss