Answer :
370 - 70 = 300
we are now left with an equal number of $20 and $10 bills to make up the $300
$20 x 10 = $200
$10 x 10 = $100
so we know that 17 bills are $10 and 10 bills are $20
we are now left with an equal number of $20 and $10 bills to make up the $300
$20 x 10 = $200
$10 x 10 = $100
so we know that 17 bills are $10 and 10 bills are $20