Mrs Durbin knows how to use texting, instant messenger, emailing, calling, and mailing letters to communicate with her students. She must select 2 methods of communication out of the 5 to send her students an important
message. In how many ways can she choose the communication methods?

step-by-step explanation:

the original amount doesn't ''re just looking for the time it takes for 1/2 of the substance to we have

(1/2) =)     take the ln   of both sides

ln (1/2)   = )   and we can write

ln(1/2) = ) lne     and lne   = 1     so we have

ln(1/2) = -.1092t     divide both sides by -.1092

t = ln(1/2)/-.1092 = about 6.347 days = about 6.3 days (rounded)

is there any photos or whatever?