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by emmelaich 254 days ago
To some, "Now we can add the two equations together to eliminate y: might need a little explanation.

The (an) answer is that since the LHS and RHS are equal, you can choose to add or subtract them to another equation and preserve equality.

If I remember correctly, substitution (isolating x or y) was introduced before this technique.

1 comments

Positive proportion - negative proportion = 0.