Step-by-step explanation: all you need to do is take the 4 and cancel it out on both sides by subracting from both sides which takes the 32 and turns it into 28 and makes the 4 disapear.
100 feet left. A yard is 3 feet. Theres 5 yards in 8 pieces. 5*3=15 and 15*8=120. He uses 4 pieces that are 5 feet. 5*4=20. He uses 20 feet. 120-20= 100.
