Help please!

Our math club has 20 members, among which we have 3 officers: President, Vice President, and Treasurer.

However, one member, Ali, hates another member, Brenda.

How many ways can we fill the offices if Ali refuses to serve as an officer if Brenda is also an officer?

(No person is allowed to hold more than one office.)

\((20\times19\times18)-(3\times2\times18) = 6840 - 108 = 6732\)

Answer see Problem 1.5, Page 5: https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=2ahUKEwjchb_Cm9rlAhUO_KQKHYg3B5QQFjAAegQIABAC&url=http%3A%2F%2Fwww.swiftclassroom.com%2Fims%2Fmath-club%2Fdocuments%2Fdownload%2FBasic%2BCounting%2BTechniques%2C%2Bpgs%2B2-17.pdf%3Fid%3D283606&usg=AOvVaw160DbZ_Rk3HOpqHfCsfyrO