Whitney has 20 coins in her purse. Some are quarters and some are dimes. The total value of the coins is $3.35. How many quarters does Whitney have?

I think it's 15 Quarters.

Step-by-step explanation:

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)

make sure you have version 2.50

try looking in the very back of the book : )

step-by-step explanation:

you can download it here