You could do it on your calculator if you have a fraction button.
otherwise
27 1/4 - 12 8/9
= 27 + 1/4 - (12 + 8/9)
= 27 + 1/4 - 12 - 8/9
= 27 - 12 + 1/4 - 8/9
= 15 +1/4 - 8/9
hopefully you will recognise that 1/4 is less than a half and 8/9 is more than a half. The first one needs to be the biggest unless you want to deal with negative numbers.
So I suggest you change 15 + 1/4 into 14 + 1 + 1/4 and, 1 and a quarter is 5 quarters.
so
=14 + 5/4 - 8/9
Now, you cannot add or subtract fractions unless the denominators (bottoms) are the same. You must find a number that 4 goes into and 9 goes into. 4*9 will work and in this case it is the smallest one.
So you will have to change it to 14 + something over 36 - something else of 36
and I am going to let you finish by yourself.
Happy puzzling.
+118677 
