Formula help

[Blue]

I need a formula to do the following

Cell A1 minus A2 = ? A1 divided by ?

Thanks Blue

 

[JE McGimpsey]

One way:

=(A1-A2)/A1

or, a bit more efficiently:

=1-A2/A1

 

[Blue]

Thanks for the reply, I need to put more explanation, I am not getting the
answer I need
The answer I need is in example below cell D1

A1 B1 C1 D1
20 15 5 1.3 in C1 =A1-B1 in D1 =A1/C1

Is it possible to do this in a formula without having to have C1 as an
actual cell

In D1 I want a formula that does A1 minus B1, divide A1 by the answer from
A1 minus B1

Help Blue

 

[Dave Peterson]

How about:
=A1/(A1-B1)

or maybe:
=if(a1=b1,"yourWarningMessageHere",a1/(a1-b1))

When a1 = b1, you'd end up with a division by zero error (#div/0!)