What whole number is closest to 6 and 3/4

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)

What are the exclude value of mn+3m

Which equation can be used to measure the density of water in a spherical water tank? let w represent the number of water particles within the region.