a car going at 20 miles per hour set out on an 80 - mile trip at 9 : 00 a . m . exactly 10 minutes later , a second car left from the same place and followed the same route . how fast , in miles per hour , was the second car going if it caught up with the first car at 10 : 30 a . m . ?
"let car a = car that starts at 9 am car b = car that starts at 9 : 10 am time for which car a travels at speed of 20 m per hour = 1.5 hours distance travelled by car a = 20 * 1.5 = 30 miles since car b catches up car a at 10 : 30 , time = 80 mins = 4 / 3 hour speed of car b = 30 / ( 4 / 3 ) = 40 miles per hour answer a"
divide(80, divide(add(multiply(subtract(10, 9), const_60), subtract(20, 10)), const_60))