Christians estimates that she will spend $250 on new summer clothes. She actually spent $350. What is the percent error? Round to the nearest whole percent

The percent error is 40%, given that $250 is the accepted value, which I think it is.

The equation to solve for percent error is (|accepted value - experimental value|) / accepted value*100 = percent error

Substitute numbers, and you get (|250-350|) / 250*100=40%