Question

two mechanics worked on a car. The first mechanic worked for 10 hours, and the second mechanic worked for 5 hours. Together they charged a total of $1600. what are the rate charged per hour by each mechanic. if the sum of the two rates are $215 per hour.

Answer 1

Let's make,
mechanic #1's rate = x
mechanic #2's rate = y

* Their rate is dollars per hour ($/hr)

mechanic #1 worked for 20 hours (hr × $/hr = $)
20x = money earned by mech#1

and mechanic #2 worked for 5 hours
5y = money earned by mech#2

together they charged a total of $1150. So the amount of money earned by both mechanics.

20x + 5y = 1150

the sum of the two rates was $95 per hour.

x + y = 95

which means
x = 95 - y

plug (95 - y) in for "x" in the other equation to get everything in terms of one variable.

20(95 - y) + 5y = 1150

solve for y

1900 - 20y + 5y = 1150
1900 - 15y = 1150
-15y = 1150 - 1900
-15y = -750
y = -750/-15
y = 50 $/hr

Now use this to solve for x

x + y = 95
x + 50 = 95
x = 95 - 50
x = 45 $/hr

mech#1 charged 45$/hr
mech #2 charged 50$/hr