# math

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solve by substitution
7x+6y=7
x=58-9y
What is the solution of the system?
(7,-5)
is this correct?

• math -

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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