Question

How to solve the system of equation 500y-600x=2800 , 400y-400x=2400 by elimination

Answer 1

Answer:

$x=2$ and $y=8$

Step-by-step explanation:

Given:

Equation 1:

$500y-600x=2800$

Simplifying the above equation by dividing both sides by 100

$\frac{500y-600x}{100}=\frac{2800}{100}$

$\frac{500y}{100}-\frac{600x}{100}=28\\\\5y-6x=28$

Equation 2:

$400y-400x=2400$

Simplifying the above equation by dividing both sides by 400.

$\frac{400y-400x}{400}=\frac{2400}{400}$

$\frac{400y}{400}-\frac{400x}{400}=6\\\\y-x=6$

Now the system of equation is:

(1a) $5y-6x=28$

(2a) $y-x=6$

Solving by elimination

Multiplying equation (2a) with $-5$

$-5(y-x)=-5\times 6$

(2b) $-5y+5x=-30$

Adding equations (1a) and (2b) in order to eliminate $y$

      $5y-6x=28$

+  $-5y+5x=-30$

We get $-x=-2$

∴ $x=2$

Plugging $x=2$ in equation (2a).

$y-2=6$

Adding $2$ both sides.

$y-2+2=6+2$

∴ $y=8$