Alright, lets get started.
Jen picked three fourth in half an hour.
Half an hour means 30 minutes.
At the same rate, how many she can pick in 2 hours.
2 hours means [tex]2 * 60 = 120[/tex] minutes
Now,
In 30minutes, Jen can pick = [tex]\frac{3}{4}[/tex]
In 1 minute, Jen can pick = [tex]\frac{3}{4} *\frac{1}{30}[/tex]
In 120 minutes, Jen can pick = [tex]\frac{3}{4} *\frac{1}{30} * 120 = 3[/tex]
Hence Jen can pick complete 3 in 2 hours of time.
So the answer is 3 : Answer
Hope it will help :)