6x - 2y + x + 5y plz answer quick.

Samantha swam upstream for some distance in one hour. she then swam downstream the same river for the same distance in only 12 minutes. if the river flows at 4 mph, how fast can samantha swim in still water?

Ben bowled 124 and 188 in his first two games. what must he bowl in his third game to have an average of at least 160?

What is the definition of exponential decay?