Let the two rates be x and y.
It was given that the sum of the two rates was $155. This means that:
The total charge is $1425. If the two mechanics worked 15 hours and 5 hours respectively at x and y dollars per hour, then it can be had that:
Subtract the two equations to solve for x:
Substitute x = 65 into the first equation:
Hence, the two rates are $65 per hour and $90 per hour.
The mechanic who worked 15 hours charged $65 per hour.
The mechanic who worked 5 hours charged $90 per hour.