Adam earns $4 for every car he washes.
He gets $2 bonus for every 4 cars he washes.

1. How much will Adam earn if he washes every 4 cars?   
2. If Adam wants to earn $30, how many cars must he wash? 
3. If Adam wants to earn $54, how many cars must he wash? 
4. If Adam wants to earn $40, how many cars must he wash? 

(a)
Amount that Adam will earn for washing every 4 cars
= 4 x 4 + 2
= $18

(b)
Number of sets of $18
= 30 ÷ 18
= 1 r 12

Number of cars in 1 set
= 1 x 4
= 4

Number of extra cars that he has to wash
= 12 ÷ 4
= 3

Total number of cars that Adam must wash
= 4 + 3
= 7

(c)
Number of sets of $18
= 54 ÷ 18
= 3 (Note that there is no remainder.)

Total number of cars that Adam must wash
= 3 x 4
= 12

(d)
If Adam wants to earn $40, how many cars must he wash?

Number of sets of $40
= 40 ÷ 18
= 2 r 4

Number of cars in 4 sets
= 2 x 4
= 8

Number of extra cars that he has to wash
= 4 ÷ 4
= 1

Total number of cars
= 8 + 1
= 9

Answer(s): (a) $18; (b) 7; (c) 12; (d) 9