Answer:
c. $400,000
Step-by-step explanation:
Let his total sales be $x.
Salary + commission =$45000
[tex] \therefore \: 25000 + 5 \% \: of \: x = 45000 \\ \\ \frac{5}{100} x = 45000 - 25000 \\ \\ \frac{1}{20}x = 20000 \\ \\ x = 20 \times 20000 \\ \\ x = \$\:400, 000[/tex]