Уравнение. 84a+25a+7=443. 4(9+7x)21=393. 486: (5x+2)=18. 5(14+ b)+6b=258

1)84а + 25а + 7 = 443
109а= 443 -7
109а = 436
а = 4
2) 4 (9 + 7х) + 21 = 393
36 + 28х + 21 = 393
28х = 393 - 21-36
28х = 336
х = 12
3) 486: (5х + 2) = 18
5х + 2 = 486:18
5х = 27 -2
5х = 25
х = 5
4) 5(14 + б) + 6б = 268
70 + 5б + 6б = 268
11б = 198
б = 18