Kenny's weight is 6/7 times Melvin's weight.

How many times the total weight of the two boys in Kenny's weight?

Answer=7:13

Kenny's Weight*6/7=Melvin's Weight

So, for example, if Melvin's weigh was 7 ...

Kenny's Weight*6/7=7

divide both sides by 6/7

Kenny Weight=6

So we can say that Melvin's weight to Kenny's weight is 7:6

The boys total weights would be ...

7+6=13

So Melvin's weight over the total weight of the two boys is:

7:13