Answer:
15 pennies
Explanation:
You can start by saying that after losing 11 pennies from his original amount it is 21-11, which equals to 10.
THen the question says that his friend gives him an additional 5 pennies, which is shown by 10+5=15
THerefore, all you had to do was use the information given and add or subtract the number of pennies from the original.
Answer: 15 pennies
Hope this helped