division between cells

im trying to set up a simple sort of program for my mum who is a proofreader where i have a list of documents then the number of pages in each document and the time taken in minutes to proofread that document. Is there a way of putting in a formula so that every time a document is proofread mum can enter the time and pages and in a 4th column it will calculate the rate of minutes per page? I'm guessing its a simple division but can't work out how 2 do it without working each one out manually each time. REALLY appreciate any help!! Thanks in advance