Josiah skateboarded from his house to school 4 miles away. It takes him 20 minutes. a. If Josiah's speed, in miles per minute, is constant, what is the constant of proportionality. * b. How many minutes will it take Josiah to skateboard to his friend Sebastian's house, which is 3 miles from school, if he travels at the same rate that he did form his house to school? *