Take the whole numbers first and do the subtraction: 13-4=9. Remember this for later. Now the fractions. We need to get them on a common basis, so what is the lowest common denominator, the smallest number that 6 and 9 both divide into exactly? To find it break down 6 and 9 into factors: 6=2*3 and 9=3*3, so they both go into 2*3*3=18. 2/9 is 4/18 (9 goes into 18 2 times multiplied by 2 is 4) and 6 goes into 18 3 times multiplied by 5 is 15, so 5/6 is 15/18. Now we subtract: 4/18-15/18. Whoops! 4-15 won't work! But we can borrow 1 from the 9 we got earlier making 9-1=8. The 1 is worth 18/18 so let's give that 4 a boost by adding 18 to it=22. Now we can take away 15 leaving 7/18. Add that to the 8 in the whole numbers and we have the answer 8 7/18.