Formula to calculate how many hours I worked in a day and eventually determine the total..

Hi, im trying to use a formula to calculate how many hours i have worked in a day from Monday to Friday and eventually get the total of hours I worked in a week.

Lets say that in column a1 I type the login time in: 10:30am on a2 its lunch out 3:00pm in a3 is lunch in 3:30pm and in a4 its time out 7:00pm what formula can i use on a5 to get the total hours worked? and I will use this same formula to do all 5 days..column A will be monday, Column B will be Tuesday etc...then at the end what formula could i use to come out with the total of hours in the week.

Thanks