Solution:
Given that;
Where, C is the cost of hiring a plumber and n represents hours worked
Mustafa and Diego both work as plumbers
a) Mustafa charges $150 to make a service call plus $50 per hour,
The equation representing the cost (C) of hiring Mustafa for n hours will be
[tex]C=150+50n[/tex]Hence, the answer is
[tex]C=150+50n[/tex]b) Diego charges $50 to make a service call plus $75 per hour,
The equation representing the cost (C) of hiring Diego for n hours will be
[tex]C=50+75n[/tex]Hence, the answer is
[tex]C=50+75n[/tex]c) Today, they both worked the same number of hours and earned the same amount of money, then,
[tex]\begin{gathered} 150+50n=50+75n \\ \mathrm{Subtract\:}150\mathrm{\:from\:both\:sides} \\ 150+50n-150=50+75n-150 \\ 50n=75n-100 \\ Collect\text{ like terms} \\ 75n-50n=100 \\ 25n=100 \\ n=\frac{100}{25} \\ n=4 \end{gathered}[/tex]Hence, they worked for 4 hours