Question 807100
Work rates add linearly, so that:



1/4 +1/5 = 1/t

t=(4*5)/(4+5)=20/9



t= 2 2/9 hours




converting the fraction to minutes

(2/9)*60= 13 1/3

1/3 of a minute is 20 sec, so...that the time is 2 hrs, 13 minutes and 20 sec