How do you solve 2x+7y=15 and x=3-2y using substitution?

Jun 4, 2016

$y = 3$

Explanation:

As $x = 3 - 2 y$, we can replace $x$in the other equation with this, turning it into

$2 \left(3 - 2 y\right) + 7 y = 15$ which when expanded

$6 - 4 y + 7 y = 15$

$6 + 3 y = 15$

$3 y = 9$

$y = 3$