Solve systems by substitution

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Learn it Solve one equation for one variable, substitute that expression into the other equation, solve, then substitute back. The solution (x, y) works in both equations.

Example: $y = 2x + 1$ and $3x + y = 16$

Substitute: $3x + (2x + 1) = 16$.
$5x + 1 = 16$, so $x = 3$.
$y = 2(3) + 1 = 7$. Solution: $(3, 7)$.

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