## Elementary Technical Mathematics

$(-1\frac{3}{5},-\frac{4}{5})$
$3x+4y=-8$ $x=2y$ Using the value for x in the second equation, substitute 2y for x in the first equation. $3(2y)+4y=-8$ $\longrightarrow$ multiply $6y+4y=-8$ $\longrightarrow$ add $10y=-8$ $\longrightarrow$ divide both sides by 10 $10y\div10=-8\div10$ $\longrightarrow$ simplify $y=-\frac{4}{5}$ Substitute $-\frac{4}{5}$ for y in the second equation. $x=2(-\frac{4}{5})$ simplify $x=-1\frac{3}{5}$