X is equal to 4
Because RS + ST=RT
So basically x+3x=5x-4
4x=5x-4
-4x -4x
-1x=-4
x=4
4.5 mph (aka 4 and 1/2 mph)
Total cost=$142
cost of parts=$62
cost paid for labour=$142-$62=$80
According to question,
》cost of labour per hr=$32
which can be written as,
》cost of labour/time=$32
Use cross multiplication,
》time=cost of labour/32
Since cost of labour is 80,
Time=80/32
=2.5hrs
