Five dozen cds were bought for $90 a peddlar sold them at 5 for $12 calculate his profit.

If 12 dozen were bought for $90 that means each CD was bought at the price of $0.66

If he sold all 60 of the CD's for 5 for $12, he'd make $144. 

Subtract the income by the original buying price to find his profit. $144 - $90

The peddler made $54 profit.

5*12=60
60 cds =$90
60/5=12( sets of CDs)
12* $12
$144-90= $54