Solve for x, y
x=7-r
y=\frac{2\left(r+2\right)}{3}
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x+r=7,2x+3y=18
To solve a pair of equations using substitution, first solve one of the equations for one of the variables. Then substitute the result for that variable in the other equation.
x+r=7
Pick one of the two equations which is more simple to solve for x by isolating x on the left hand side of the equal sign.
x=7-r
Subtract r from both sides of the equation.
2\left(7-r\right)+3y=18
Substitute -r+7 for x in the other equation, 2x+3y=18.
14-2r+3y=18
Multiply 2 times -r+7.
3y=2r+4
Subtract -2r+14 from both sides of the equation.
y=\frac{2r+4}{3}
Divide both sides by 3.
x=7-r,y=\frac{2r+4}{3}
The system is now solved.
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