Question 399727: Attempting to solve what looks like a simple problem, but keep coming up with the incorrect answer.
5/4z - 3/8z
The problem is written as a fraction, with one term directly above the other. I've done the best I can to represent this here.
I came up with 2/4z, which I simplify to 2z. Can you help?
Answer by solver91311(24713)   (Show Source):
You can put this solution on YOUR website!
Presuming you mean:
rather than
which is an equally valid interpretation of what you wrote, proceed as follows:
Find the LCD of 4 and 8. Both 4 and 8 divide 8 evenly, so 8 is the LCD.
Convert  . You have to multiply the denominator by 2 to get from 4 to 8, so you have to multiply the numerator by 2 as well. Result:
Now you can add the numerators. 10 plus -3 is 7, so:
Now, for where I think you may have gone wrong. You added 5 and -3 to get 2 and then simply ignored the fact that you had a different denominator in the second fraction. Then, having erroneously decided that the sum was  , you changed  into 2.
Let's see if your arithmetic makes any sense. I have one whole pizza and a quarter of a pizza. The whole pizza is sliced into 8 slices, and the quarter pizza is two slices. I give you the whole thing and tell you to eat what you want and calculate what you have when you are done. You eat 3 of the slices and then, according to your arithmetic, you have 2 whole pizzas left. I never believed that loaves and fishes story either.
John
My calculator said it, I believe it, that settles it
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