B) 11.11 (11 rounded); Divide 50 by 18 to get the amount of minutes per mile (2.77) then multiply that by 4 which equals 11.11
C) 21.61 mph (22 rounded) ; There are 10 minutes left until an hour has passed, divide 10 by 2.77 (minutes per mile) to find the distance that would have been traveled (3.61). Finally add the 2 amounts, 18+3.61=21.61