Question 762230
Uniform rate, and the rate of each person when working together is additive using their rates.


Tommy:  1 job per 9 hours, rate is 1/9 jobs per hour.
Huck:  1/t jobs per hour, we do not know this t.
Tommy+Huck: 1 job per hour.


Look carefully that the units used here are as JOBS PER HOUR, where 1 job means, "paint the fence".


Rates of each are additive, as already said.
{{{highlight(1/9+1/t=1)}}}
Find t.