## Elementary Technical Mathematics

$5x-y=18$ $y=\frac{1}{2}x$ Substitute $\frac{1}{2}x$ for y in the first equation. $5x-\frac{1}{2}x=18$ $\longrightarrow$ simplify $4\frac{1}{2}x=18$ $\longrightarrow$ divide both sides by 4.5 $4\frac{1}{2}x\div 4\frac{1}{2}=18\div4\frac{1}{2}$ $\longrightarrow$ simplify $x=4$ Substitute 4 for x in the second equation. $y=\frac{1}{2}(4)$ $\longrightarrow$ simplify $y=2$