Tom earns $40 a week mowing lawns. He spends 1/10 of his earnings on lunch and 4/5 of his earnings on music. He saves the rest. How many dollars does Tom save?

Answer: $4

Step-by-step explanation:

Tom earns $40 a week when he now lawns.

Amount earned by Tom = $40

Fraction spent on lunch = 1/10

Fraction spent on music = 4/5

Fraction saved = 1 - (1/10 + 4/5)

= 1 - (1/10+8/10)

=1 - (9/10)

=1/10

Amount saved = 1/10 * 40

= $4

Tom saves $4 out of the weekly amount he means by mowing lawns.