How much fencing does she need to buy

Its is surprising that no one attempted this question for over a week.

As in all geometry problems, start with a diagram (shown).

Then we realize right away that AB=sqrt(8^2+2^2)=sqrt(68)=2sqrt(17)

BC=sqrt(4^2+1^2)=sqrt(17)

The perimeter is therefore twice the sum of AB+BC=2(2sqrt(17)+sqrt(17))

2(3sqrt(17))=6 sqrt(17) We can estimate sqrt(17)=4.125, so 6sqrt(17)=24.75 which is close enough to get the correct answer choice.

Have a good day.