The manufacturing cost of a cell phone was $124. sellers first marked up the cost by 20 percent. sales were poor, so sellers decreased the markup to 15 percent. calculate the old and new selling prices.

If the phone costs $ 124 ,and first was marked up by 20 % it means that it was for sale for
124+(124*20)100=124+24.80= $148.80
if the seller decreased the mark up to 15% then the phone costs now
124+(124*15)/100=124+18.60= $ 142.60