1) 8x – 4x + 5 = 25;
4x + 5 = 25;
4x = 25 – 5;
4x = 20;
x = 20 : 4;
x = 5;
2) (y – 12) ⋅ 36 = 1260;
y – 12 = 1260 : 36;
y – 12 = 35;
y = 35 + 12;
y = 47;
3) 851 : (13 + x) = 37;
13 + x = 851 : 37;
13 + x = 23;
x = 23 – 13;
x = 10;
4) (x – 12) : 13 = 82;
x – 12 = 82 • 13;
x – 12 = 1066;
x = 1066 + 12;
x = 1078.