How can you tell which tape diagram you need

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)

Which of the following contains a variable?

Which of the following is best modeled using a linear equation y=ax+b, where a is less than 0?