Time Calculation with Breaks

Mark has a school project that requires him to measure time intervals. He starts by recording the time when he begins doing his project and finishes 1 hour and 45 minutes later. He takes a break of 20 minutes during the project. What is the total time Mark spent working on the project, excluding breaks?

To find the total working time, you need to subtract any breaks from the total time spent which includes the break. How many minutes in total did Mark work on the project?