SOLUTION: 2x + 3y=21 4x + 2y =22

Question 26356: 2x + 3y=21
4x + 2y =22
Answer by wuwei96815(245) (Show Source): You can put this solution on YOUR website!
Multiply first equation by -2. We get -4x - 6y = -42.

Now, add the altered first equation to the second equation. We get -4y = -20.

Solve -4y = -20. We get y = -20/-4 = 5.

Now that we have the value for y we can go back and substitute this value in either of the original equations and solve for x. Let's use the first equation.
2x +3y = 21
2x +3(5) = 21
2x +15 = 21
2x = 21 - 15 = 6
x = 6/2 = 3

This method for finding two unknowns with two equations is called the addition/substitution method. There are other methods for doing this problem also.
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