Posted by **jason** on Monday, June 29, 2009 at 11:44pm.

solve by substitution

7x+6y=7

x=58-9y

What is the solution of the system?

(7,-5)

is this correct?

- math -
**Marth**, Tuesday, June 30, 2009 at 9:48am
You can check your work by using the values you found for x and y in the equations to see if they match.

7(7) + 6(-5) = 7

49 - 30 = 7

19 = 7

7 = 58 - 9*(-5)

7 = 58-45

7 = 13

Clearly, something is wrong.

Substitute 58-9y for x in 7x+6y=7 (because x = 58-9y)

7(58-9y) + 6y = 7

406 - 63y + 6y = 7

399 - 57y = 0

399 = 57y

y = 7

x = 58 - 9y

x = 58 - 9*7

x = 58 - 63

x = -5

The answer is (-5,7). Always (x,y).

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