How do you do 4 and 6? can you guys tell me step by step? : )

In the sixth grade 13 out of 20 students have a dog if there are 152 sixth grade students how many of them have a dog

Randy and trey take turns cleaning offices on the weekends. it takes randy at most 4 hours to clean the offices. it takes trey at most 6 hours to clean the offices. what is the greatest amount of time it would take them to clean the offices together? 2.4 hours 2.5 hours

Which angle has the same measure as the dehedral angle formed by the orange face and the purple rectangle