Math CentralQuandaries & Queries


Question from Devon, a student:

Solve for y. 3x - 2y = 12

Hi Devon,

You have two variables x and y and you are to solve for one of them. Let me illustrate with a different example.

Solve for t. 5t - 4s = 8

Since you are to solve for t you want to end with an expression of the form

t = "some expression that doesn't involve t."

Since I want t alone on the left side I would add 4s to both side to obtain

5t - 4s + 4s = 8 + 4s
5t = 8 + 4s

Now divide both sides by 5 to get

5t/5 = (8 + 4s)/5
t = 8/5 + 4/5 s

I hope this helps,

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