SOLUTION: How do you solve this: 3 5/6 -7 1/2. I tried using 12 as the lcd and still now coming up with the right answer. We're doing signed numbers right now and it is confusing me a lot ..

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Question 10869: How do you solve this: 3 5/6 -7 1/2. I tried using 12 as the lcd and still now coming up with the right answer. We're doing signed numbers right now and it is confusing me a lot ...is there a simple rule to remember
Answer by longjonsilver(2297) (Show Source):
You can put this solution on YOUR website!
the strictly correct version of this is as follows:

3 and 5/6 is 23/6 in total (since the 3 is 18/6)
7 and 1/2 is 15/2 in total (since the 7 is 14/2)

so we have 23/6 - 15/2, which we cannot do, since the 2 denominators are different. We need them to be the same number: 12 would do fine, but why not choose 6? This is far less work :-)

15/2 --> 45/6

So, now we have 23/6 - 45/6
which is -22/6

which is -3 and 4/6
or, better, -3 and 2/3

jon.