A shopper paid $51.93 including tax for an item marked $48.99. What would she pay for another item m

A shopper paid $51.93 including tax for an item marked $48.99. What would she pay for another item marked $75?

Set up a proportion, assuming identical tax rates:
51.93/48.99 = 75/x where x is the after-tax amount

Using our proportion calculator, we get:
x = 70.75