excel percentages

[richard]

Feels like a very embarrassing question to ask but here goes.

I have a number of sales for a year (C3), and a percentage increase on the
previous year (C7). I need a formula to show the sales for that previous year.

eg 105 and 5% would be 100.

I know this is probably more a maths question than an excel question but I
can't seem to get anything to work - I keep coming up with 99.75 rather than
100.

Thanks for helping.

 

[JE McGimpsey]

One way:

=C3/(1+C7)

 

[ShaneDevenshire]

Hi Richard,

Here is the logic for future reference:
if y =100 and p= 5% and you want to know x

x=y*p+y
x=y*(p+1)
but you know x and you want to know y so
y*(p+1)=x
y=x/(p+1)

with your cell address this is
=C3/(C7+1)