Explanation:
the manufacturing costs are defined by
m(x) = 25x + 150
the selling revenue is defined by
s(x) = 50 + 30x = 30x + 50
clearly, the selling amount is bigger than the manufacturing amount (also supported by the fact that 30x > 25x). otherwise the company is going bankrupt in no time.
so,
a)
the profit is (as usual) revenue minus manufacturing :
p(x) = 30x + 50 - 25x - 150 = 5x - 100
b)
x = 150
p(150) = 5×150 - 100 = 750 - 100 = $650
since the result is positive, yes, they are making a profit. and it is $650.