Amusic store buys compact discs for $12 each and sells them for $15 each. what is the percent of markup on these compact discs?
a. 3%
b. 20%
c. 25%
d. 80%

can someone me?

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.