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Addition of equations
We want to solve two equations with two unknowns. That means, that you determine the intersection point of two straight lines
Method 1
Usually the first method you learn is to express x in y in both equations
Now we take the results, and find
Cross multiplication gives
By entering y in one of the equations you get x.
It's all rather cumbersome, and if you're not careful you can quickly make arithmetical mistakes.
Method 2
There is a simpler method to solve the equations. If you work like this, you can save a lot of time.
It is obvious how this works, so no further explanation is needed. You just have to make sure that the x's or the y's disappear.