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.