Explanation:
1) m<CDN = m<CDE - m<NDE = 180-156 = 24°
2) m<KLV = m<KLM - m<VLM = 178-158 = 20°
3) m<UVW = m<UVT + m<TVW
172 = 21x+1+149x+1 = 170x+2
Subtract 2, 172-2 = 170x => 170 = 170x. So, x=1
4) m<ABC = m<ABN + m<NBC
100 = 2x+13+5x+17
100 = 7x+30
70 = 7x. => x=10
5) m<JKL = m<JKE +m<EKL
129 = x+88+43+x
129 = 2x+131
-2 = 2x => x=-1
m<JKE = x+88 = -1+88 = 87°
6) m<GHI = m<GHK + m<KHI
178 = x+40+x+162
178 = 2x+202
-24 = 2x => x=-12
m<GHK = x+40 = -12+40 = 28°
7) m<ABC = m<ABL + m<LBC
23x+8 = 29+21x-7
2x = 14 => x=7
m<LBC = 21x-7 = 21*7 - 7 = 147 - 7 = 140°