If a is the center of the circle, which of these is/are diameters

Acyclist bike x distance at 10 miles per hour .and returns over the same path at 8 miles per hour.what is the cyclist average rate for the round trip in miles per hour ?

Which two fractions are equivalent to 24/84? 6/42 and 2/7 6/21 and 2/6 12/42 and 3/7 12/42 and 2/7

Which unit rate is the lowest price per ounce? (5 points) choice a: 6 ounces of chocolate chips for $2.49 choice b: 8 ounces of chocolate chips for $3.32