Вставьте пропущенное слово: In 1980s it became possible via _ and cable TV to use more channels on a TV set at every home on the world

1)10d-1

2)18-30b

3)100-20m

 

 

 

 

1) 26+d+9d-27=10d-1
2)54-(31b-36)+b=54-31b+36+b=90-30b=3(3-b)
3)50-10(2m-5)=50+20m+50=100+20m=20(5+m)