I really need help. I couldn't figure it out. Please check it out. :)​

What is the common denominator for 3/5+3/4

Every weekday, mr. jones bikes from his home to his job. sometimes he rides along two roads, the long route that is shown by the solid lines. other times, he takes the shortcut shown by the dashed line. how many fewer kilometers does mr. jones bike when he takes the shortcut instead of the long route?

There are 93 calories in a small candy bar how many calories are ther in a half dozen small candy bars?