Ted can change an advertisement on a billboard in 3 hr . Marie can do the same job in 5 hr , How long would it take them if they worked together? Write your
answer as a fraction or mixed number, If necessary.
Together, Ted and Marie can do the job in

To find out how long it takes Ted and Marie to complete the job together, we first determine their individual rates. Ted can complete the job in 3 hours, so his rate is 1/3 of the job per hour. Marie completes the job in 5 hours, giving her a rate of 1/5 of the job per hour.

By adding their rates together, we have:

1/3 + 1/5 = (5/15) + (3/15) = 8/15 of the job per hour.

To find the time they take together to finish the job, we take the reciprocal of their combined rate:

Time = 1 / (8/15) = 15/8 hours or 1 and 7/8 hours.

Together, Ted and Marie can do the job in 1 and 7/8 hours.