3. After going to the mall, you and your friend go eat lunch at a restaurant. The final bill, including a 20% tip, is $31.80. Write and Solve an equation to find the amount of original bill for food you ate.

To keep cylindrical tanks from tipping over, a designer is planning to enlarge the original area of the base by 50%. the new tank should have the same volume as the original. how should the designer change the height of the tank? a: make it 50% taller than the height of the original tank. b: make it 6623% taller than the height of the original tank c: make it 3313% shorter than the height of the original tank d: make it 50% shorter than the height of the original tank.