Answer:
3.6 hours
Explanation:
To solve, create a Rate, Time, Work chart:
Work is rate times time. For Kevin, his work is going to equal x over 6 job. For Anna, her expression for work will equal x over 9 job.
The work is 1 job of calling all clients, so their combined work is equal to 1.
x over 6 plus x over 9 equals 1
In the rational equation, x is the amount of time it takes Kevin and Anna to call the clients together. With rational equations, the terms can be added together once they have common denominators.
x over 6 plus x over 9 equals 1
fraction numerator begin display style x left parenthesis 9 right parenthesis end style over denominator begin display style 6 left parenthesis 9 right parenthesis end style end fraction plus fraction numerator begin display style x left parenthesis 6 right parenthesis end style over denominator begin display style 9 left parenthesis 6 right parenthesis end style end fraction equals fraction numerator begin display style 1 left parenthesis 6 right parenthesis left parenthesis 9 right parenthesis end style over denominator left parenthesis 6 right parenthesis left parenthesis 9 right parenthesis end fraction
fraction numerator 9 x over denominator 54 end fraction plus fraction numerator 6 x over denominator 54 end fraction equals 54 over 54
9 x plus 6 x equals 54
15 x equals 54
x equals 3.6
If Kevin and Anna work together, they can call all the clients in 3.6 hours.