Найдите корни уравнения: 1)-0,5х+13,8=12,4; 2)х÷(-3)-20,1=-21,9; 3)2,5÷х+2,812=-7,188; 4)-91,2+(-2х)=-100,7.

1)-0.5x+13.8=12.4
-0.5x=12.4-13.8=-1.5
x=-1.5:-0.5
x=3
2) x÷(-3)-20.1=-21.9
x÷(-3)=-21.9+20.1=-1.8
x=-3×-1.8=5.4
3) 2.5÷x+2.812=-7.188
2.5=x=-10
x=-4
4) -91.2+(-2x)=-100.7
-2x=-91.2+100.7=9.5
x=9.5:-2=-4.75