Chapter 9 - Section 9.1 - Solving Systems of Linear Equations in Three Variables and Problem Solving - Practice - Page 635: 6

20 degrees, 60 degrees, 100 degrees

small = s, medium = m, large = r $r=80 + s$ $m=40+s$ $s+m+r=180$ $s + (40+s) + (80+s) = 180$ $3s+120=180$ $3s=60$ $3s/3=60/3$ $s=20$ $r=80+s$ $r=80+20$ $r=100$ $m=40+s$ $m=40+20$ $m=60$