Suppose Diego deposits $4,000 in his bank. If the reserve ratio is 10 percent, this will lead to a maximum increase of ________ in checking account...

Suppose Diego deposits $4,000 in his bank. If the reserve ratio is 10 percent, this will lead to a maximum increase of ________ in checking account balances throughout all banks..

A) $0

B) $4,000

C) $10,000

D) $40,000

Suppose Darrell has $4,000 in currency which he deposits in his bank. If the reserve ratio is 25 percent, this will lead to a maximum increase of ________ in M1 throughout all banks.

A) $0

B) $4,000

C) $6,000

D) $12,000

which formula should I use? a detailed answer would be helpful!