As given by the question
There are given that the statement
The first mechanic worked for 20 hours and the second mechanic worked for 5 hours.
Now,
Suppose, the mechanic first-rate is x and the mechanic second rate is y
Then,
The first mechanic works are 20x and the second mechanic works are 5 y
According to question;
Together they charged $1650
So,
The amount of money that earned by both mechanics
[tex]20x+5y=1650[/tex]
Now,
The sum of the two rates was $165 per hour
Then,
[tex]x+y=165[/tex]
That means,
[tex]x=165-y[/tex]
Then,
Put the value of x into the above equation, 20x+5y=1650
So,
[tex]\begin{gathered} 20x+5y=1650 \\ 20(165-y)+5y=1650 \\ 3300-20y+5y=1650 \\ 3300-15y=1650 \\ 3300-15y-1650=0 \\ 1650-15y=0 \\ 1650=15y \\ y=\frac{1650}{15} \\ y=110 \end{gathered}[/tex]
Now,
Put the value of y into the equation, x+y=165
So,
[tex]\begin{gathered} x+y=165 \\ x+110=165 \\ x=165-110 \\ x=55 \end{gathered}[/tex]
Hence, the mechanic first charged is $55 per hour and mechanic second is $110 per hour.