First line up and add together all of your whole numbers.
7+8+4=
Then add up all of your fractions. I like to set them up in columns one above the other. That way when you change the denominators you can see them easier.
looking at all the denominators we can see that they all have a 6 in common. So change them all to a 6, remember what you do to the bottom you have to do to the top. Multiply 2/3 top and bottom by a 2, Multiply 1/2 top and bottom by 3 and the last is 1/6 so you don't need to change that one. Now you can add all the tops together and end up with 8/6. This is improper divide the bottom into the top and you have 1 and 2/6 left over. This will reduce to 1 and 1/3. NOW go back and add this to the whole parts that you added up first. The final answer should be 20 and 1/3/