How do you write 72.1 as a fraction

What number should be added to both sides of the equation to complete this square? x^2-10x=7

To determine the number of deer in a forest a forest ranger tags 280 and releases them back

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)