Three times a number plus 12 minus 5 times the same number is 22

1. a number is represented by "x" 

3x + 12 - 5x = 22 
12 - 2x = 22 
-2x = 10 
x = -5 

2. (45) + (45) + (45 + 6x) = 303 
job 1, 2, 3 equals total for the day 

135 + 6x = 303 
6x = 168 
x = 28 

the plumbers hourly rate is $28/hr

Three times (3 ·) a number (x) plus (+) 12 minus (-) 5 times (·) the same number (x) is (=) 22

3x + 12 - 5x = 22   Combine like terms (3x and -5x)
      -2x + 12 = 22   Subtract 12 from both sides
              -2x = 10   Divide both sides by -2
                 x = -5