[Willowlynn]

What if the bottom number is differnet?

5/9 = -y + 2/15

how do I get the common number? Oh how I feel old tonight.

[hghent]

What is the common number of 9 and 15?? 45

so... 25/45=-y+6/45

[Kmchamplin]

5/9 = -y + 2/15
- 2/15 + 5/9 = -y + 2/15 - 2/15 (subtract -2/15 from each side to get y by itself?
-2/15 + 5/9 = -y

-6/45 + 25/45 = -y (common number in lower numbers is 45 so you have to multiply the top number in the first one x 3 to get -6and 5 in the second one)

19/45 = -y

Flip flop the - and make it -19/45 =y