A formula to work out hours on a staff rota

Hi all, I'm new to the forum and would be so grateful if someone could help me. I'm compiling a staff rota (attached) which has various shifts and would like to be able to have a box next to or under each shift that has calculated the hours for each, then a box totaling these hours at the end of the week, so I can ensure each member of staff has their allocated hours.

Thanks in advance

Tiger