Sophie bikes s miles per hour. Her friend, Rana, is slower. Rana bikes r miles per hour. c
Rana and Sophie went for a 20-mile bike ride today. Each girl biked at her usual speed. How long did Sophie wait for Rana at the end of the route?

A33 gram sample of a substance that's used to detect explosives has a k-value of 0.1473. n = noekt no = initial mass (at time t = 0) n = mass at time t k = a positive constant that depends on the substance itself and on the units used to measure time t = time, in days