10. The bill (including parts and labor) for the repair of an oven was $142. The cost

of parts was $62 and the cost of labor was $32 per hour. How many hours were

spent repairing the oven? 2'5

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