"z=y10^(-kt), where y and k are positive constants.
i) Give the physical interpretation for the constant y."
I have no idea what this means but I wrote ylog_10_z = -kt
"ii) Show that log_10_z = -kt+log_10_y"
By my workings, it really doesn't, so something is wrong. I've been stuck on this for days and it's due tomorrow.
Note: I know all the logarithm rules, but none of them seem to apply here.