hrlp

You'll have to convert the fractions to fractions with a common denominator:

1 3/4  -  5/6  =    1  9/12  - 10/12       Now, '1' =  12/12   Yah?

So we can make this look like this:

12/12 + 9/12 -10/12   OK?

(12+9-10)/12 = 11/12       cool???

11/12