11. x = 16
complementary angles add up to 90°.
angle 1 and angle 2 added together will equal 90°.
42 + 3x = 90
subtract 42 on both sides.
3x = 48
divide by 3 on both sides.
x = 16
12. x = 26
supplementary angles add up to 180°.
angle c and two times the value of x (2x) will equal 180°.
128 + 2x = 180
subtract 128 on both sides
2x = 52
x = 26
hope this helps!
