Part A:
to find the amount of money the interior designer will make as a function of hours we need to find f(g(x)), so:
[tex]\begin{gathered} g(x)=\frac{1}{7}x \\ f(g(x))=49(\frac{1}{7}x)^2-200 \\ f(g(x))=49(\frac{1}{49}x^2)-200 \\ f(g(x))=x^2-200 \end{gathered}[/tex]so the answer is: x^2-200
Part B:
we can use the equation we just found, so x is the number of hours so x=50 and we need to find f(g(x))
[tex]50^2-200=2300[/tex]so the answer is: 2300