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How do u solve x+5y=20 and -2x+7y=45 by elimination

User Morendo
by
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1 Answer

6 votes

Answer:

x = -5; y = 5

Explanation:

x + 5y = 20

-2x + 7y = 45

Multiply both sides of the first equation by 2 to get 2x. Write the second equation below it and add the equations. 2x and -2x add to zero eliminating the x terms.

2x + 10y = 40

-2x + 7y = 45

-----------------------

17y = 85

y = 85/17

y = 5

Now use substitution in the first original equation to find x.

x + 5y = 20

x + 5(5) = 20

x = -5

Answer: x = -5; y = 5

User Janki
by
6.7k points