Question

Solve the equations using the method of substitution method :
$3x+4y=-43$ and $-2x+3y=11$

• A. 7 and 5
• B. 5 and -7
• C. -5 and 7
• D. 5 and 7

Answer 1

The correct option is D 5 and 7

$3x+4y=-43$ ------- (1)
$-2x+3y=11$ ------ (2)
From equation 1:
$3x+4y=-43$
$4y=43-3x$
$y=\frac{43-3x}{4}$
Substitute the value of $y$ in equation 2:
$-2x+3\left(\frac{43-3x}{4}\right)=11$
$-8x+129-9x=44$
$-17x=44-129$
$x=\frac{-85}{-17}=5$
The substitute the value of $x$ in equation 1:
$3x+4y=43$
$3\left(5\right)+4y=43$
$15+4y=43$
$4y=43-15$
$4y=28$
$y=\frac{28}{4}$
$y=7$
Therefore the solution is: $x=5$ and $y=7$