We can't subtract because they don't have the same
denominator. The LCD of 9 and 6 is 18, because
both will divide evenly into 18. So we change 
to 
and 
to 
We still can't subtract because the upper fraction
has a smaller numerator than the lower fraction .
So we borrow 1 from the 9, leaving it with 8, and that gives
us 
to add to the fraction which just amounts
to adding the denominator 18 to the numerator 10, getting 28, so
we have this:
And now we can subtract because the numerator above is bigger
than the numerator below. So 8 minus 6 gives 2 for the whole part
of the answer, and 28-15 gives 13 for the numerator of the answer
so we subtract and get:
Edwin
