Find each percent increase round to the nearest percent from 13 friend to 14 friends

From 13 friends to 14 friends. The number of friends is increased by 1.

To get the percentage of increase:

(14 - 13) / 13 = 1 / 13 = 0.0769 * 100% = 7.69%

The increase of 1 friend is equivalent to 7.69% increase.

13 is the basis. It is the 100%
 1 is the increase. It is the 7.69%
14 is the total number of friends. It is the 107.69% = 100% + 7.69%

Ralph is earning 2.8% commission

11 mintues is the naswer