M=90 2m+235+4m-125-5m = 19980: (7x-15) = 54 285 - (x:14-481) = 36*6 3 * (7+42) - 8x=4041

1) Упростим выражение:

2 * m + 235 + 4 * m - 125 - 5 * m = (2 + 4 - 5) * m + 110 = m + 110;

При m = 90:

90 + 110 = 200.

2) 19980 : (7 * x - 15) = 54;

19980 : 54 = 7 * x - 15;

370 = 7 * x - 15;

7 * х = 370 + 15 = 385;

х = 385/7 = 55.

3) 285 - (x : 14 - 481) = 36 * 6;

285 - (x : 14 - 481) = 216;

x : 14 - 481 = 285 - 216;

x : 14 = 69 + 481;

х = 14 * 550 = 7700.

4) 3 * (7 + 42) - 8 * x = 4041;

3 * 49 - 8 * x = 4041;

147 - 8 * x = 4041;

-8 * x = 3894;

х = 3894 / (-8) = - 1947/4.