Answer each of the following independent questions concerning supplies and the adjustment for supplies.

a. The balance in the supplies account, before adjustment at the end of the year, is $7,000. What is the amount of the adjustment if the amount of supplies on hand at the end of the year is $2,200?

b. The supplies account has a balance of $1,300, and the supplies expense account has a balance of $3,900 at the end of the first year of operations. What was the amount of supplies purchased during the year?