Answer:
6 hours
Step-by-step explanation:
For Bob
12 hours = 1 fence
1 hour = 1/12 fence
Together Bob and Jen
4 hours = 1 fence
1 hour = 1/4 fence
Now, for Jen:
1 hour = 1/4 - 1/12= 3/12 - 1/12 = 2/12=1/6
Find the amount of time Jen will need:
1/6 fence = 1 hour
1 fence = 6 hour
Using the distributive property, a(b+ c) = ab + ac. In this case, b is 30, so the blank is 30.
