In a class of 30 students, everyone has either a pierced nose or a pierced ear. the professor asks everyone with a pierced nose to raise his or her hand. eight hands go up. then the professor asked everyone with a pierced ear to do likewise. this time there are 25 hands raised. how many students have piercings both on their ears and their noses?

It is saturday morning and jeremy has discovered he has a leak coming from the water heater in his attic. since plumbers charge extra to come out on the weekends, jeremy is planning to use buckets to catch the dripping water. he places a bucket under the drip and steps outside to walk the dog. in half an hour the bucket is 1/5 of the way full. what is the rate at which the water is leaking per hour?