Please help look at picture and round to the nearest tenth

What are “like terms”? why can we only add like terms?

Find the distance between (0,5) & (-4,2)

Out of the 180 students at a summer camp, 72 signed up for canoeing. there were 23 students who signed up for trekking, and 13 of those students also signed up for canoeing. use a two-way table to organize the information and answer the following question: approximately what percentage of students signed up for neither canoeing nor trekking? 72% 40% 54% 98%