Answer:
23 minutes 9.47 seconds.
Step-by-step explanation:
The groundskeeper's rate is 1=r*40 so r = 1/40 of the job per minute. The assistant works at a rate of 1/55 of the job per minute (1 = r*55 so r=1/55).
To find the time when they work together, use the equation with their combined rate: 1/40 + 1/55 = 19/440
1 = 19/440 * t so t = 440/19 = 23 and 3/19 minutes or 23 minutes 9.47 seconds.
