Question 1158207
Mark's rate of work = 1/4 ditch per hour
Greg's rate of work = 1/3 ditch per hour
<pr>
Rate of work working together = (1/4 + 1/3) ditch per hour = (3/12 + 4/12) ditch per hour = 7/12 ditch per hour
<pr>
If they can dig 7/12 of the ditch per hour working together, this means it will take them 12/7 hour to dig the ditch working together.
<pr>
12/7 hours...or 1-5/7 hours...is about 1 hour and 43 minutes.