so percent means parts out of 100 so
7%=7/100=0.7/10=0.07/1=0.07
so we want to find 12.50 +7% of 12.50
'of' can be translated as multiply
12.50+(0.07 times 12.5)=12.5+0.88=13.38
the total cost is 13.38
a shortcut is if you want to find cost+tax then
cost=1 and tax=0.07 so 1+0.07=1.07 so to find cost, just multply by 1.07
