Question

Given the equation below what is the value of y-x? 3x+4=-5y+8 9x+11y=-8

Answer 1

Answer:

$-5$

Step-by-step explanation:

$3x+4=-5y+8\\9x+11y=-8$

Rearrange the first equation and substitute it into the second equation.

$3x=-5y+8-4\\3x=-5y-4$

(as we want 9x instead of 3x we are going to multiply this equation by 3)

$9x=-15y-12\\-15y-12+11y=-8\\-4y=4\\y=-1$

Rearrange the first equation and substitute in our y value to solve for x.

$3x+4=-5(-1)+8\\3x=5+8-4\\3x=9\\x=3$

Hence

$y-x=-1-4=-5$