Two mechanics worked on a car.
Now, mechanic 1 has spent 5 hours working on the car.
Mechanic 2 has spent 15 hours working on the car.
Lets say mechanic 1 charged 'x' dollars per hour and mechanic 2 charged 'y' dollars per hour.
So,
that is our first equation ( 1 ):
And,
that is our second equation ( 2 ):
Using the two equations we can solve for 'x' and 'y', using our first equation we get:


On solving for 'x' and 'y' we get:

and putting the value of 'y' in the equation 2 we get:

As mentioned earlier, 'x' represents the charge that mechanic 1 charged per hour and 'y' represents the charge that mechanic 2 charged per hour.
We have
and
.
So, the mechanic 1 charged $75 per hour and mechanic 2 charged $80 per hour.