I dont understand this problem. Could someone explain it to me?

Fiona races bmx around a circular dirt course. if the radius of the course is 70 meters, what is the total distance fiona covers in two laps of the race? a. about 30,772 meters b. about 15,386 meters c. about 879.2 meters d. about 439.6 meters e. about 219.8 meters23 points hurry

Given f(x)=2x^2-8x+6 and g(x)=3x-1 find f(x) +g(x) a. 2x^2+5x+5 b.2x^2-11x+7 c. 2x^2-5x+5 d.2x^2-5x-5

Mrs. morton has a special reward system for her class. when all her students behave well, she rewards them by putting 3 marbles into a marble jar. when the jar has 100 or more marbles, the students have a party. right now, the the jar has 24 marbles. how could mrs. morton reward the class in order for the students to have a party?