Math police come my way please?

Kelli swam upstream for some distance in a hour.she then swam downstream the same river for the same distance in only 6 minutes.if the river flows at 5km/hr, how fast can kelli swim in still water?

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%?

Finley's pumpkin had a mass of 6.5 kilograms before he carved it. after carving it, the pumpkin had a mass of 3.9kg. what was the percent decrease in the mass of the pumpkin?