A fruit salad mixture consists of apples, peaches, and grapes in the ratio of 6:5:2, respectively, by weight. If 39 pounds of the mixture is prepared, the mixture includes how many more pounds of apples than grapes?

What I did:

6+5+2= 13

39/13 (for the whole over the part) = 3

Then I multiplied 3 times each of the ratio numbers to get 18:15:6 and so the difference from the apples to grapes is 18-6 = 12. Is the answer 12 correct?