12x+342=44
12x=44-342
12x=-298
x= -298/12
x= -24 10/12
x= -24 5/6
9y+9y=18
18y=18
y=18/18
y=1
14x-10x=20
4x=20
x=5
20-50y*10=30
20-500y=30
-500y=30-20
-500y=-10
y=-10/(-500)
y=0.02
5x-10-19x=20
5x-19x=20+10
-14x=30
x=30/(-14x)
x= -2 2/14
x=-2 1/7
20x+20x=40
40x=40
x=1