Please help me on this math question i will give u a

Find the greatest common factor of 28 and 35

The circumference of a circle is 5 pi cm. what is the area of the circle?

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