[jpsb]

fractions are easy if you are adding or subtracting just find the common denominator. A fail safe method is to multiply the bottom of the faction to get a denominator and then cross multiply from bottom to top.

Example 1/2 + 2/3

multiply bottom 2 x 3 = 6 so 6 is the denominator

now cross multiply bottom to top

2 x 2 = 4 so we have 4/6

3 x 1 = 3 so we have 3/6

now add 4 + 3 = 7

so our answer to 1/2 + 2/3 is 7/6

easy.

[jpsb]

One more example

11/13 - 5/8

13 x 8 = 104 so 104 is the denominator

13x5 = 65 so 65/104

8x11 = 88 so 88/104

88 - 65 = 23 so 11/13 - 5/8 = 23/104

23/104 is meaningless to most people so

23 is pretty close to 25 and 104 is pretty close to 100 so 23/104 is pretty close to 1/4 (25/100) but since we had to grow 23 to get to 25 and shrink 104 to get to 100 we are really looking a something a little smaller then 1/4. Call it almost 1/4.

[Principled]

no problem with your explanation... but I will say that it is an adding fractions analog to the subtraction example in this thread.

Just an example.

[gunsequalfreedom]

fractions are easy if you are adding or subtracting just find the common denominator. A fail safe method is to multiply the bottom of the faction to get a denominator and then cross multiply from bottom to top. Example 1/2 + 2/3 multiply bottom 2 x 3 = 6 so 6 is the denominator now cross multiply bottom to top 2 x 2 = 4 so we have 4/6 3 x 1 = 3 so we have 3/6 now add 4 + 3 = 7 so our answer to 1/2 + 2/3 is 7/6 easy.

Easy? Sorry, you lost me right after "multiply the bottom of the faction to get a denominator and then cross multiply from bottom to top."