The school band earned $10/family * 3 families = $<<10*3=30>>30 from three families.
The school band earned $15/family * 5 families = $<<15*5=75>>75 from 15 families.
The school band earned $30 + $75 = $<<30+75=105>>105 total.
The school band needs $150 - $105 = $<<150-105=45>>45 more to reach their goal.
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