David is tracking the amount of water he drinks each day. On Thursday, he drinks 15 cups of water.
On Friday, he drinks 12 cups of water.
What is the percent change in his water intake?

Out of the 150 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?