Math Is Fun Forum

Hi,

I didn't really much pay attention to Fractions in school and am about go off to university. I think I have them pretty much down pat (Thanks to this site ) but am having trouble with an example from a textbook called "Understanding Year 8 Maths" by Warwick Marlin. I can't understand what he is doing with with Example 3 on Page 61 which is:
  6m + 4m
  10     5
= 6m + 8m
    10    10
= 14m
    10
= 7m
    5

It looks like what he is doing is cross multiplying and then dividing the numerator by the original denominator before finding the lowest common denominator.

But if he was doing that, then wouldn't the fraction on the left be 3m over 10? If not, then where did the 8m come from?

I thought that when adding fractions you needed to cross multiply the numerators with the denominators on the opposite sides and then find the lowest common denominator before adding the numerators?

Thanks for the help in advance!