32 + (136-х*8) : 4=64; 21=75: (2 х+13)) * 5+120; 12 * (32 - (36+8 х) : 5) + 144;

1) 32 + (136 - х * 8) : 4 = 64;

(136 - х * 8) : 4 = 64 - 32;

(136 - х * 8) : 4 = 32;

136 - х * 8 = 32 * 4;

136 - х * 8 = 128;

136 - 128 = х * 8;

8 = х * 8;

х = 8 : 8;

х = 1.

2) 21 = 75 : (2 х + 13) * 5 + 120;

21 - 120 = 75 : (2 х + 13) * 5;

-99 = 75 : (2 х + 13) * 5;

-99 * (2 х + 13) * 5 = 75;

-99 * (2 х + 13) = 75 : 5;

-99 * (2 х + 13) = 15;

-198 х - 1287 = 15;

-198 х = 15 + 1287;

-198 х = 1302;

х = 1302 : (-198);

х = - 6 19/33.

3) 12 * (32 - (36 + 8 х) : 5) = 144;

32 - (36 + 8 х) : 5 = 144 : 12;

32 - (36 + 8 х) : 5 = 12;

32 - 12 = (36 + 8 х) : 5;

20 = (36 + 8 х) : 5;

20 * 5 = 36 + 8 х;

100 - 36 = 8 х;

64 = 8 х;

х = 64 : 8;

х = 8.