|4t+n| if t = -2 and n = 5 for algebra 1

Find the solution of this system of equation -7x+y=-20 9x-3y=36

The ratio of the measures of the three angles in a triangle is 2: 9: 4. find the measures of the angels

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)