Question 10869
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.