Solve for x
x=4y-18
Solve for y
y=\frac{x+18}{4}
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-5x+5y+15y-90=0
Combine 5x and -10x to get -5x.
-5x+20y-90=0
Combine 5y and 15y to get 20y.
-5x-90=-20y
Subtract 20y from both sides. Anything subtracted from zero gives its negation.
-5x=-20y+90
Add 90 to both sides.
-5x=90-20y
The equation is in standard form.
\frac{-5x}{-5}=\frac{90-20y}{-5}
Divide both sides by -5.
x=\frac{90-20y}{-5}
Dividing by -5 undoes the multiplication by -5.
x=4y-18
Divide -20y+90 by -5.
-5x+5y+15y-90=0
Combine 5x and -10x to get -5x.
-5x+20y-90=0
Combine 5y and 15y to get 20y.
20y-90=5x
Add 5x to both sides. Anything plus zero gives itself.
20y=5x+90
Add 90 to both sides.
\frac{20y}{20}=\frac{5x+90}{20}
Divide both sides by 20.
y=\frac{5x+90}{20}
Dividing by 20 undoes the multiplication by 20.
y=\frac{x}{4}+\frac{9}{2}
Divide 90+5x by 20.
Examples
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{ x } ^ { 2 } - 4 x - 5 = 0
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4 \sin \theta \cos \theta = 2 \sin \theta
Linear equation
y = 3x + 4
Arithmetic
699 * 533
Matrix
\left[ \begin{array} { l l } { 2 } & { 3 } \\ { 5 } & { 4 } \end{array} \right] \left[ \begin{array} { l l l } { 2 } & { 0 } & { 3 } \\ { -1 } & { 1 } & { 5 } \end{array} \right]
Simultaneous equation
\left. \begin{cases} { 8x+2y = 46 } \\ { 7x+3y = 47 } \end{cases} \right.
Differentiation
\frac { d } { d x } \frac { ( 3 x ^ { 2 } - 2 ) } { ( x - 5 ) }
Integration
\int _ { 0 } ^ { 1 } x e ^ { - x ^ { 2 } } d x
Limits
\lim _{x \rightarrow-3} \frac{x^{2}-9}{x^{2}+2 x-3}