At 2: 30 p. m., cayson leaves his house and drives north to the stadium. he arrives at 5: 00 p. m. also leaving at 2: 30 p. m., his brother riley leaves his house and drives south to a lake. he arrives at 5: 30 p. m. the driving distance from the stadium to the lake is 385 mi. cayson and riley drove at the same speed. what was their speed?