The cost C, in dollars, to produce graphing calculators is given by the function C(x)=57+4500, where x is the number of calculators produced. How many calculators can be produced if the cost is limited to $129,900?

Answer 1

I will assume you have a typo and you meant to type
C(x)=57x+4500

so solve
129000 = 57x + 4500

( get x = 2184)