How do you solve the system $2 x - 3 y = 21$ $2x-3y=21$ and $y = 3 - x$ $y=3-x$ using substitution?

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Answer 1 · 2017-03-03T08:05:00

$x = 6$ $x=6$ & $y = - 3$ $y=-3$
Solution : $(6, - 3)$ $(6,-3)$

$2 x - 3 y = 21$ $2x-3y=21$ ------------(1)

$y = 3 - x$ $y=3-x$ -----------------(2)

Substituting eq 2 in eq 1

$2 x - 3 (3 - x) = 21$ $2x-3(3-x)=21$

$2 x - 9 + 3 x = 21$ $2x-9+3x=21$

$5 x - 9 = 21$ $5x-9=21$

$5 x = 30$ $5x=30$

$x = 6$ $x=6$

Put $x = 6$ $x=6$ in eq 2 we get,

$y = 3 - 6$ $y=3-6$

$y = - 3$ $y=-3$

Solution : $(6, - 3)$ $(6,-3)$

How do you solve the system 2x−3y=212x-3y=21 and y=3−xy=3-x using substitution?