Solve for x
x=12
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12.5=8.1+0.4x-0.4
Use the distributive property to multiply 0.4 by x-1.
12.5=7.7+0.4x
Subtract 0.4 from 8.1 to get 7.7.
7.7+0.4x=12.5
Swap sides so that all variable terms are on the left hand side.
0.4x=12.5-7.7
Subtract 7.7 from both sides.
0.4x=4.8
Subtract 7.7 from 12.5 to get 4.8.
x=\frac{4.8}{0.4}
Divide both sides by 0.4.
x=\frac{48}{4}
Expand \frac{4.8}{0.4} by multiplying both numerator and the denominator by 10.
x=12
Divide 48 by 4 to get 12.
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