Question 599096
the equatio is right 
now for determining the maximum value for x set the derivative of the equation equal to zero
f(x)=(600 - 30x) (15 +1x) = 9000+600x-450x-30x^2
f'(x)= 600-450-60x=0
150=60x , x=5/2=2.5
maximun value for hat : 15+x=15+2.5=17.5
f(x) is the total profit = (600-30(2.5))(17.5)= 9187.5