Ok I leaned excel back in the day when I was taking cs/is 101

Now I have forgotten it completely. Can you please help?

I want the amount in column B to be divided by 100 and multiplied by
5(basically I want 5 percent.) post the data to column L

I also want to Add column c,d,e,f show results in G then subtract the
total (G) from column B

Then I want column N to be divided by 2 and to be displayed into M


I know that this isn't the usual questions asked but well this is
what I need right at the moment I am running xp home and I have office
2002

I don't want to go through the tutorial because I know if I try it
out and play with it for 3 days I will remember everything again.