Solve for x
x = \frac{45}{4} = 11\frac{1}{4} = 11.25
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3x+45+x=90
Add x to both sides.
4x+45=90
Combine 3x and x to get 4x.
4x=90-45
Subtract 45 from both sides.
4x=45
Subtract 45 from 90 to get 45.
x=\frac{45}{4}
Divide both sides by 4.
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