Is #19. for a correct and can someone explain this to me ?

Simplify a7/a4 a) 1/a3 b)-a/a2 c)a4/a3 d)a3

The pyramid shown has a square base that is 24 centimeters on each side. the slant height is 16 centimeters. what is the lateral surface area?

Abag contains 10 white golf balls and 6 striped golf balls. a golfer wants to add 112 golf balls to the bag. he wants the ratio of white to striped gold balls to remain the same. how many of each should he add?