Verified answer

iPod

$30 * 0.15 = $4.5

$4.5 +30 = $34.5

or for a shortcut: $30*1.15 = $34.5

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Stereo

decrease by 29% means 1-0.29 = 0.71

It is 71% of the original value.

$90*0.71 = $63.90

find 15% of $30......change 15% to .15 and x $30

.15 x 30 = $ 4.50

now add that to the original price of $30....= $34.50

decrease by 20%

find .20 x $90 = $90x. = 18.00

now subtract $90 - 18 = $72.