Answer:
see explanation
Step-by-step explanation:
All of these questions use the external angle theorem, that is
The external angle of a triangle is equal to the sum of the 2 opposite interior angles.
18
∠3 = 43° + 22° = 65°
19
∠2 + 71 = 92 ( subtract 71 from both sides )
∠2 = 21°
20
90 + ∠4 = 123 ( subtract 90 from both sides )
∠4 = 33°
21
2x - 15 + x - 5 = 148
3x - 20 = 148 ( add 20 to both sides )
3x = 168 ( divide both sides by 3 )
x = 56
Hence ∠ABC = x - 5 = 56 - 5 = 51°
22
2x + 27 + 2x - 11 = 100
4x + 16 = 100 ( subtract 16 from both sides )
4x = 84 ( divide both sides by 4 )
x = 21
Hence ∠JKL = 2x - 11 = (2 × 21) - 11 = 42 - 11 = 31°
