Please give me the correct answer.​

5x + 2 = 12 solve the following equation. then place the correct number in the box provided.

Robert is placing sod in two square shaped areas of his backyard. one side of the first area is 7.5 feet. one side of the other area is 5.7 feet. the sod costs y dollars per square foot

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?