hello

i have created an invoice in one sheet in excel, on the invoice i have this
columns:

item number, quantity, description, parts price, labor, and total amount.

i put the item number, the quantity, and the description, but now the
problems are the parts price, the labor, and the total amount, because i want
in the total amount cell, that multiplies the value on quantity times the
value on the cell in the colum of parts price, bit "if" it has a value, if
the labor colum has a value, then the operation has to be quantity times the
value of the labor colum.

first my question is if is that possible, then can somebody help me?

it is a matter of work. please help.

thx.