I need help with 3 math questions. Here they are: A study of 50 high school students showed that exactly 25 of them took Biology, exactly 20 of them took Chemistry, and exactly 12 of them took both subjects. How many of the 50 students took neither Biology nor Chemistry? From a pile of coins containing nickels (N), dimes (D), and quarters (Q), Tom picked 10 coins with a total value of $1.00. The 10 coins had a different number of each of the three types and at least 1 coin of each type. How many coins of each type did he pick? An Olympiad team is made up of students from the 4th, 5th, and 6th grades only. Seven students are 5th graders, eleven students are 6th graders, and one third of the entire team are 4th graders. How many students are on the team? If you can even answer one question that would be very helpful! Thanks a lot!