Define r to be the binary relation on z such that: xry iff xy is r an equivalence relation?

Average acceleration: i have no idea how to do this.

You are at a restaurant and owe $38 for your meal. you want to leave a 20% tip. how much will your tip be?

Ihave a triangle with a 60 degree angle. lets use d for that angle. what are the values of e and f if d is 60 degrees? and what do you notice about the values of e and f?