If a wheel with a radius of 30 inches spins at a rate of 500 revolutions per minute, find the approximate linear velocity in miles per hour.

30 inches @ 500 rpm = 15,000 inches per minute

15,000 inches per minute = 900,000 inches per hour (multiply by 60)

1 mile = 5,280 feet (google-able fact you shouldn't have to memorize)
1 foot = 12 inches (you probably already know this)
900,000 inches = 75,000 feet (divide by 12)

75,000 feet = 14.20454545454545. . . miles (divide by 5280)

Linear velocity in miles per hour is 14.20454545454545. . . miles per hour.

J= r + 9 because since jessica rode 9 more miles than roger, you add 9 miles to rogers mileage.