Answer
Solution: $(\displaystyle \frac{280}{11},\frac{70}{11})$
(checked below)
Work Step by Step
Step 1
Substitute $x$ with $4y$ in the second equation and solve for $y$
$ 3(4y)-y=70\quad$
$12y-y=70$
$11y=70$
$y=\displaystyle \frac{70}{11}$
Step 2
Substitute $y$ with $\displaystyle \frac{70}{11}$ in the other equation and solve for x.
$4(\displaystyle \frac{70}{11})=x$
$x=\displaystyle \frac{280}{11}$
Write the solution as $(x,y)$
Solution: $(\displaystyle \frac{280}{11},\frac{70}{11})$
Check: $\left[\begin{array}{lll}
4\cdot\frac{70}{11}\stackrel{?}{=}\frac{280}{11} & ..... & 3\cdot\frac{280}{11}-\frac{70}{11}\stackrel{?}{=}70\\
\frac{280}{11}=\frac{280}{11} & & \frac{840-70}{11}=70\\
& & \frac{770}{11}=70\\
& &
\end{array}\right]$
