Question

Solve the following pair of equations:

$13+2y=9x$, $3y=7x$

• A. $x=6$; $y=-7$
• B. $x=5$ ; $=13$
• C. $x=-7$; $y=1$
• D. $x=3$; $y=7$

Answer 1

The correct option is D $x=3$; $y=7$

We pick either of the equations and write one variable in terms of the other.

Let us consider the equation $3y=7x$ and write it as

$x=\frac{3}{7}y..........\left(1\right)$

Substitute the value of $x$ in the equation $13+2y=9x$ or $9x-2y=13$. We get:

$9\left(\frac{3}{7}y\right)-2y=13\Rightarrow 27y-14y=91\Rightarrow 13y=91\Rightarrow y=7$

Therefore, $y=7$

Substituting this value of $y$ in Equation (1), we get

$x=\frac{3}{7}\times 7=3$

Hence, the solution is $x=3,y=7$.