liam is pulled over for speeding just as he is arriving at work . he explains to the police officer that he could not afford to be late today , and has arrived at work only four minutes before he is to start . the officer explains that if liam had driven 5 mph slower for his whole commute , he would have arrived at work exactly on time . if liam ' s commute is 20 miles long , how fast was he actually driving ? ( assume that liam drove at a constant speed for the duration of his commute . )
"let t be the number of hours he would need to reach office on time . when he is driving with over speed , he reached office 4 min earlier ! so the equation for this is s ( t - 4 / 60 ) = 20 where s is the speed and 20 is the distance . if he decreases his speed by 5 mph then he would have reached his office on time : ( s - 5 ) t = 20 if you solve above equations , you will arrive at t = 2 / 3 hr and s = 40 mph therefore answer is e"
add(20, multiply(5, const_4))