How to find the answer

2,400cm^2

Step-by-step explanation:

Surface area of square: 20 × 20 = 400

Times six sides: 400 × 6 = 2,400

Brielle will run the marathon faster.

Brielle = 104.8 minutes  

Joshua = 157.2 minutes

Step-by-step explanation:

Speed rate = distance /time

Brielle = 1.25 /10 = 0.125 miles per minute

Joshua = 1.5/18 = 0.083333 =1/12 miles per minute

Since 0.125 (Brielle) > 1/12 (Joshua)

Brielle will run the marathon faster.

To calculate the time that takes each one to run the entire race (13.1 miles)

Time= distance / speed

Feel free to ask for more if needed or if you did not understand something.