A dog kennel charges $40 to board a dog for one night and $35 per night each night after that. Henry paid a total of $215 for dog boarding. For how many nights did Henry board his dog?

Need on this one asap im almost done with this subject

An energy drink company claims that its product increases students' memory levels. to support its claims, the company issues advertisements claiming that 8 out of 10 people (chosen randomly from across the country) who tried their product reported improved memory. the missing component in this study is a .

Could somebody me with this radical simplification?