Hey guys, just found this forum after searching for days about this problem I've got. No where seems to have any relevant answers so I thought I might ask a forum for some help.

Basically I've got a Methods Assignment and I can't seem to work out if what I am doing is correct, any help would be great.

Here's the question:

The mass of a radioactive isotope is given by M=Mo(10)^-kt. It takes 200 years for the mass of the isotope to halve.

Find the initial mass (grams) in terms of M.

I assume Mo_{10}(10) is the initial mass and a logarithm, doesn't say though.

I've tried to solve this question like this:

M=Mo_{10}(10)^{-kt}

M=(-kt)Mo_{10}(10)

M/Mo_{10}(10)=-kt

Mo_{10}(10)/M=1/-kt

Mo_{10}(10)=-M/kt

Is this correct or have I made some kind of mistake, just doesn't seem right to me :/