Josie is making fruit salad for a party. she bought 1 1/2 pounds of apples, 1 3/4 pounds of cherries, and 2 2/3 pounds of grapes. how many pounds of grapes did josie buy in all?

2 and 2 3rds lol. You just told me she bought 2 2/3rds pounds of grapes

Are you asking how many pounds of grapes or fruit?  (I think you mean fruit because the amount of grapes is given already.)  Put mixed fractions in improper form with like denominators first:
1 1/2 = 2/2 + 1/2 = 3/2  
1 3/4 = 4/4 + 3/4 = 7/4  
2 2/3 = 3/3 + 3/3 + 2/3 = 6/3 + 2/3 = 8/3
12 is the lowest common denominator so multiply the tops and bottoms of these fractions by whatever will make the bottom = 12
(6/6) x (3/2) = 18/12
(3/3) x (7/4) = 21/12
(4/4) x (8/3) = 32/12
Now we can add them because the denominators are equal:
18/12 + 21/12 + 32/12 = 71/12
this is 5 11/12 cups fruit