If the average of 5 weight is 13lbs then gets increasd by 7lbs how much is the average of the six weights?

If the average of 5 weights is 13lbs then the total weight is 5 x 13 = 65 lbs.

If 7lbs is added the total weight of 6 items becomes 65 + 7 = 72 lbs.

The average weight now becomes 72/6 = 12 lbs.