remember
all angles add to 180
x+y+z=180
one is 2 times as another
x=2y
measure of 3rd angle (z) is 20 more than smalllest
since y has to be doubled to get x, y is smallest
z is 20 more than y
z=20+y
we have
x=2y
z=20+y
sub those
x+y+z=180
2y+y+20+y=180
4y+20=180
minus 20 both sides
4y=160
divide 4
y=40
sub back
x=2y
x=2(40)
x=80
z=20+y
z=20+40
z=60
the angles are
80 degrees, 40 degrees, 60 degrees