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

Please help me solve this, I have about 3 hours and I dont understand how to solve this

Respuesta :

Answer:

[tex]x=2[/tex] and [tex]y=8[/tex]

Step-by-step explanation:

Given:

Equation 1:

[tex]500y-600x=2800[/tex]

Simplifying the above equation by dividing both sides by 100

[tex]\frac{500y-600x}{100}=\frac{2800}{100}[/tex]

[tex]\frac{500y}{100}-\frac{600x}{100}=28\\\\5y-6x=28[/tex]

Equation 2:

[tex]400y-400x=2400[/tex]

Simplifying the above equation by dividing both sides by 400.

[tex]\frac{400y-400x}{400}=\frac{2400}{400}[/tex]

[tex]\frac{400y}{400}-\frac{400x}{400}=6\\\\y-x=6[/tex]

Now the system of equation is:

(1a) [tex]5y-6x=28[/tex]

(2a) [tex]y-x=6[/tex]

Solving by elimination

Multiplying equation (2a) with [tex]-5[/tex]

[tex]-5(y-x)=-5\times 6[/tex]

(2b) [tex]-5y+5x=-30[/tex]

Adding equations (1a) and (2b) in order to eliminate [tex]y[/tex]

      [tex]5y-6x=28[/tex]

+  [tex]-5y+5x=-30[/tex]

We get [tex]-x=-2[/tex]

∴ [tex]x=2[/tex]

Plugging [tex]x=2[/tex] in equation (2a).

[tex]y-2=6[/tex]

Adding [tex]2[/tex] both sides.

[tex]y-2+2=6+2[/tex]

∴ [tex]y=8[/tex]

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