how do i subtract a negative number

[anndee]

i am creating a profit and loss statement in excel. the problem that i am
having is for example: food sold - cost of food =sum(c1-c6) but if my
food sold is zero and my cost of food is a negative number this equation
gives me a positive number. i want a general equation that will give me the
correct answer if the numbers in the equation are positive or negative

 

[CLR]

=IF(C6>=0,C1-C6,C1+C6)

Vaya con Dios,
Chuck, CABGx3

 

[JE McGimpsey]

What *is* the correct answer if your revenue from sales is zero, and
your costs are negative (I'm assuming you got a refund)?

If you're entering costs as negative numbers, then you just have to add
revenue and cost:

= C1 + C6

(Note that the SUM() function in your example is not necessary).