6.11 180-38=142

6.13 a)x+x+30=180

2x=150

x=75

б)x-y=40

x+y=180

x=180-y

180-2y=40

-2y=-220

y=110

x=180-110=70

в)x+4x=180

x=36

4x=180-36=144

г)x+x=180

x=90