Answer: 
Work Shown:

Therefore -7 goes in the first box, and
goes in the second box.
584 = 8 hours
146 = 2 hours (divide each side by four)
Answer: fg
and
Domain: All real number. All real number or 
Explanation:
fg means product of two given function f(x) and g(x)
where,
and 
Now, we have to find fg
So, fg=
Substitute f(x) and f(x)

Using distributive property simplify above expression and we get,

We can see it is cubic polynomial. So, domain of cubic polynomial is all real number.
Domain: All real number or 
We need to start from the innermost parenthesis and work our way out.
The first parenthesis is
. These are not like terms because one involves a variable, while the other is a constant term. Two terms are summable if they involve the same power(s) of the same variable(s).
So, we can take one step outwards, and we arrive to the square brackets. We have

and 2z and -13z are like terms, so we can sum them:

Finally we arrive to the whole expression, which is

Because, again, 5z and 11z were like terms.