Hi there can anyone up here that's is really good in math me with this question

Which matrix multiplication is possible?

Acylinder has volume 45π and radius 3. what is it’s height?

How do i start to solve? would appreciate a walk-thru! a bird sitting 16ft above the ground in an apple tree dislodges an apple. after how many seconds does the apple land on the ground? (assuming that no branches will interfere with it's fall)