Question

if you triple 4 and subtract to each day how many days until you have zero

Answer 1

do you mean subtract two each day? If so...
4x3=12 and 12 divided by 2 is 6 so it would take six days to reach zero
or
you could manually subtract two from 6 each days as in 12-2=10 (1 day), 10-2=8 (2 days), and so on...