Question 283296
Frank works at a rate of 1/4 job per hr.
James works at a rate of 1/7 job per hr.
It takes them 'x' hours to do one entire job.
x*(1/4) + x*(1/7) = 1
.
x/4 + x/7 = 1
.
7x + 4x = 28
.
11x = 28
.
x = 28/11 = 2.54545
.
check by seeing how much of the job each does in 2.54545 hr
2.54545*1/4 = .6363
2.54545*1/7 = .3636
.6363+.3636 = .9999, which is pretty close to 1 whole job
.
Answer:
Working together it takes them 2.54545 hrs.
Or about 2 hr 33 min
.
Done