sums with fractions

[ducey99]

what are the formulas for adding/subtracting/multiplying and dividing fractions

[chrisrob]

A very quick fractions primer.
I hope the spacings are OK. Sorry but you'll have to imagine the lines between the tops and bottoms of the fractions.

Follow these 2 examples:
1)
1 + 2
4 3 (one quarter plus two thirds)

Find the smallest number the two bottom numbers will go into exactly (=12)
Multiply both top and bottom numbers of each fraction by the same number to get that number at the bottom.

For 1
4 multiply both by 3 to get 3
12 (three twelfths which is the same as a quarter)

2
3 multiply both by 4 to get 8
12

three twelfths plus eight twelfths is eleven twelfths

2)

1 x 2
2 3 (one half times two thirds)

Multiply both top numbers together ( 1 x 2 = 2) and both bottom numbers together ( 2 x 3 = 6) and the answer is two sixths which is the same as one third.

[chrisrob]

Sorry, as I feared, the spacings make this very difficult to interpret.
1) One quarter becomes three twelfths and two thirds becomes eight twelfths. Three twelfthd and eight twelfths make eleven twelfths,

[chrisrob]

Looking at how my reply posting appeared, I am ashamed. I spent 30 years teaching this stuff to year 6 and 7 pupils but how my answer displayed would cofuse rather than help. To see how it should have appeared, follow this link:
http://robichris.googlepages.com/fractions
Perhaps someone who is more used to AB will tell me how I can better format text here (including emboldening and underlining etc)?

[factor-fiction]

see here for tutorial on bold, italics underlining:
http://www.theanswerbank.co.uk/ABTutorial.html
You can get simple fractions on Word etc using insert and can then paste into your AB answer