Barack wants to buy 15 tickets to take his friends to a play. The tickets cost $2.50 each. How much will all the tickets cost together?

37.50

Step-by-step explanation:

if you multiply 2.50 to 15 you get 37.50

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)