Step-by-step explanation:
Using log properties


Then

Plug in the knowns


Answer:
33993.0768
Step-by-step explanation:
You can multiply the number of bacteria by (0.2^4). The 0.2 is for the 20% that left after each day. The (^4) is for the 4 days that have passed.
assuming you means k = log_2(3) [as log(2)3 is the same thing as 3log(2) due to multiplication being commutative]
given log(ab) = log(a) + log(b)
log_2(48) = log_2(3) + log_2(16)