Rearrange the second equation to solve for x:
x + 3x = 4 + 2y + 1
4x = 5 + 2y
x = (5 + 2y)/4
Substitute this expression for x into the first equation:
2(5 + 2y)/4 + y = -7
Multiply both sides of the equation by 4 to eliminate fractions:
2(5 + 2y) + 4y = -28
10 + 4y + 4y = -28
8y = -38
y = -38/8
y = -19/4
Substitute this value for y back into the expression for x:
x = (5 + 2(-19/4))/4
x = (5 - 19/2)/4
x = (10 - 19)/8
x = -9/8
So the solution is (x, y) = (-9/8, -19/4)
Solve for (x,y) in the system of equations
2x + y = -7
x = 4 + 2y - 3x + 1
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