Find the sum of 8x + 4y and -2x - 3y

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?

The table shows the results of three plays in a football game. what is the net result of the three plays? football game 1st play 5 yards 2nd play -9 yards 3rd play 12 yards

Atriangle has side lengths of x, x+11, and 3x+5. what is the perimeter?