Answer:
54000
Explanation:
Amount sold by federal reserve in treasury bonds to a bank = 50,000
Interest on treasury bonds =

So, interest charged on treasury bonds =

Immediate effect on money supply :
The immediate effect is that amount of money in bank increases by

Amount of money in bank = Amount sold by federal reserve in treasury bonds to a bank + Interest on treasury bonds = 50000 + 4000 = 54000