After paying $3 for a sandwich, Trevor has $9.How much money did he have before buying the sandwich?

Rename mixed numbers before you can subtract are what

The angle of a triangle are given as 6x,(x-3), and (3x+7). find x then find the measures of the angles

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)