You can put this solution on YOUR website! These are usually easier if you clear your decimals. In this case you can do that by multiplying both sides by 10.
.6(x-50)=18-0.3(40-10x)
10[.6(x-50)]=10[18-0.3(40-10x)]
(10)(.6)(x-50)=(10)(18)+(10)(-0.3)(40-10x)
6(x-50)=180-3(40-10x)
(6)(x)+(6)(-50)=180+(-3)(40)+(-3)(-10x)
6x-300=180-120+30x
6x-300=60+30x
-30x+6x-300=60+30x-30x
-24x-300+300=60+300
-24x=360
-24x/-24=360/-24
x=-15
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