alexquiroga831 alexquiroga831
  • 01-12-2020
  • Mathematics
contestada

What is the value of x in the solution to this system of equations?

4x+7y=85

x=2y−5

A. x = -9
B. x = 9
C. x = 8
D. x = 3

Respuesta :

sophiew4
sophiew4 sophiew4
  • 01-12-2020

Answer:

B

Step-by-step explanation:

I used substitution to solve this system. I'll run through all of my steps below:

[tex]4x+7y=85\\x=2y-5[/tex]

I'm going to replace the 'x' values in the first equation with the entire second equation.

[tex]4(2y-5)+7y=85[/tex]

[tex]8y-20+7y=85\\15y-20=85\\15y=105\\y=7[/tex]

Now that we know what y equals, we can go back and solve for x.

[tex]x=2(7)-5\\x=14-5\\x=9[/tex]

Hope this helps!

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