SOLUTION: 30/10+y = 20/10-y

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Question 40339: 30/10+y = 20/10-y
Answer by smik(40) About Me  (Show Source):
You can put this solution on YOUR website!
Good Question. I'm guessing you meant 30/(10+y) = 20/(10-y).
Anyway, our first aim is to get rid of the denominators because those don't help a lot when solving equations. So we can first multiply both sides by (10+y) and then multiply both sides by (10-y).


%2810%2By%29%2A%2830%2F%2810%2By%29%29+=+%2820%2F%2810-y%29%29%2A%2810%2By%29 (we multiply both sides by 10+y)


30+=+%2820%2A%2810%2By%29%29%2F%2810-y%29


%2810-y%29%2A30+=+20%2A%2810%2By%29 (we multiply both sides by 10-y)


We can factor this out:


300-30y+=+200%2B20y


100+=+50y (subtract 200 from both sides, and add 30y to both sides)


y+=+2 (the final answer)