Y varies directly as x and inversely as the square of z. y=57 when x = 27 and z = 3. Find y when x = 50 and z = 5.
y =

1. a music store marks up the instruments it sells by 30%. a. if the store bought a guitar for $45, what will be its store price? b. if the price tag on a trumpet says $104, how much did the store pay for it? c. if the store paid $75 for a clarinet and sold it for $100, did the store mark up the price by 30%?