When it comes to math i usually have an indication as to what I am supposed to do but this task was completely impossible for me.

M(t)=53e^{-t/223}

t=amount of years. I am supposed to calculate when the function has decreased by 1/3 of it's original size using logarithmical laws. This time I can't show you my steps because I don't even know where to begin!

I also have this problem that i find equally difficult.

(e^{x}-5)/(5e^{-x}-4)=2

I don't even know where to begin and it's driving me absolutely insane lol, would a kind soul please help me ?