Question

During the lockdown period your ATM card stopped workingas it got deactivated after its date of
expiryYou could not step out to go to your bank .Write a letter to the Manager of your bank requesting
him to issue a new ATM card at the earliest .You may use your name, address and Bank Name
Here is a format you would like to use .​

Answer 1

Answer:

a cistern can be filled by taps a and b in 10 minutes and 12 completely in 7 minutes. if all three taps are turned on the same time find the time taken to fill the cistern