The answer is:
The correct option is:
A) Jeff, 4.5 hours; Julia 9 hours.
<h2>Why?</h2>To solve the problem, we need to write two equations using the given information.
So, writing the first equation we have:
We know that Jeff can weed the garden twice as fas as his sister Julia, so:
Also, from the statement we know that they can weed the garden in 3 hours, so, writing the second equation we have:
Then, we need to substitute the first equation into the second equation in order to isolate Julia's rate, so, solving we have:
We have that Julia could weed the garden by herself in 9 hours.
So, calculating how long will it take to Jeff, we have:
We have that Jeff could weed the same garden by himself in 4.5 hours.
Hence, the correct option is:
A) Jeff, 4.5 hours; Julia 9 hours.
Have a nice day!