how do you calculate an old salary if the only information you have is current salary and the percentage increase received. For example if I make $15.86 an hour and I received a 7% increase, how much did I used to make? Thanks.


This is a place where a little bit of algebra really helps. Suppose that you let x be the number of dollars per hour that you used to make. Then,

x plus 7% of x is $15.86. That is

x +  7/100 x = (1+ 7/100)x = 1.07 x = $15.86. Thus

x = $15.86/1.07 = $14.82

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