Rex is currently taking physics as one of his electives in school. His grade at the end of the year is determined by the average of four exams, each worth 100 points. On his first test he got an 84, on his second he got a 86, and on his third an 92. What must he score on his fourth exam to get an A (90%) in the course? a. 98 b. 90 c. 88 d. 86

Math i have no idea how to do a and b

Me with this assignment ! i only partially understand, so explain. also it's a work sample. at the championship bike race, steve and paula were fighting for first place. steve was 175 feet ahead of paula and had only 300 feet left to go. he was very tired and was going only 9 feet per second. paula was desperate to catch up and was going 15 feet per second. who won the bike race and by how far did she/he win?

Ms. green tells you that a right triangle has a hypotenuse if 13 and a leg of 5. she ask you to find the other leg of the triangle. what is you're answer?