10+2(x)=5(x-7)
10+2(x)=5(x)-35
35+10=5(x)-2(x)
45=3(x)
45/3=x
x=15
Do the same thing as the attached image.
First of all, you want the variable to be isolated, so in order to do that, you divide in both sides. Ten divided by two is five. So f = 5.
2f + 10
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2 2
10 divided by 2 = 5
$13.53 is the answer to you problem