Locker Rent received = 17,050.
Less: Previous year's (2020-21) outstanding received now = 3,050 (not current year's income).
Add: Current year outstanding (receivable for 2021-22) = 1,500.
Less: Advance received for next year = 1,000.
Current year income = 17,050 - 3,050 + 1,500 - 1,000 = 14,500.
Being income, it is credited to Income and Expenditure A/c.