А) - 20 * (х - 13) = - 220 б) (30 - 7х) * 8 = 352
х - 13 = - 220 : (- 20) 30 - 7х = 352 : 8
х - 13 = 11 30 - 7х = 44
х = 11 + 13 7х = 30 - 44
х = 24 7х = - 14
х = - 14 : 7
х = - 2
в) 5/12у - 3/4 = 1/2
5/12у = 1/2 + 3/4 = 2/4 + 3/4 = 5/4
у = 5/4 : 5/12 = 5/4 * 12/5 = 12/4
у = 3