Answer:
Roberto did 4 or 5 hours
Step-by-step explanation:
r- Roberto
e- Edward
j- Jim
j = 1 hr. paddled
r= 2e for the number of hours, r, robert paddled.
r+ e+ j < 10 Substitute in for r and j.
2e+ e+ 1 < 10
3e <9
e< 3
r = 2*e
r < 2*3 I Changed it to less than, so because edward has to do less than 3 hours, so now im finding the number of hours that he has to be below.
r<6
Roberto did less than 6 hours.
Edward did less than 3 hours.
Jim did 1 hour.
Possible Combination of hours that satisfies all the criteria and is below 10 total hours:
Jim Does 1 hour, Edward does 2 hours, and Roberto does 4 hours.
Another Possibility is
Jim does 1 hours, Edward does 2.5 hours and Roberto does 5 hours.
(Edward has to do 2.5 hours for Roberto to do 5 hours, because it states that Roberto does twice as many hours as Edward, it does not state that he did more than twice as many hours so it is necessary for Edward to do 2.5 hours for Roberto to do 5.)
So,