Since the plumber charges 92$ for less than 4 hours,

it could be for a job which finishes in 1,2,3 or 4 hours.

The additional 23$ is charged for every additional hour that the plumber works.

We have been asked to find out, how much the plumber charges for both the work.

1. The plumber charged $92 for one of the two jobs.

If the plumber charges 92$ for one of the jobs, he could have finished the work in 1 hour or 4 hours.

If he had finished the work in 1 hour, he would have 6 hours to do the other work

(making the charge for the second work 92 + 2*23= 138$)

Total(Amount charged) : 92 + 138 = 230$However, If he had finished the work in 3.5 hours, he would have 3.5 hours to do the other work

(making the charge for the second work 92$ only)

Total(Amount charged) : 92 + 92 = 184$ Clearly insufficient

2. The plumber charged $138 for one of the two jobs.

If the plumber charges 138$ for one of the jobs, he could have finished the work in 6 hours.

Charges for the work(which lasted 6 hours) 92 + 2*23= 138$)

Total(Amount charged) : 92 + 138 = 230$As minimum charges for any work is 92$, if it takes less then 4 hours.

(Sufficient) (Option B)
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