solve( 2x-3=4, y=x+2 ) => {x=(7/2), y=(11/2)}
http://en.wikipedia.org/wiki/Line_(geometry)
with \(P_0 = ( x_0, y_0 )\) and \(P_1 = (x_1, y_1)\) the equation for the line passing through P0 and P1 is:
\((y - y_0)(x_1 - x_0) = (y_1 - y_0)(x - x_0)\)
or
\(y=x\,\frac{y_1-y_0}{x_1-x_0}+\frac{x_1y_0-x_0y_1}{x_1-x_0}\,.\)
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