The correct answer is 720. Just turned it in and got a 100. Good luck and hoped this help ya.
Answer:
perimeter: 26
area: 16 + 10 =26
perimeter: add all lengths.
area: multiply LxW
Find the rate in which both balls make one full rotation around the track.
Ball A:

It takes 30 seconds for Ball A to make a full rotation.
Ball B:

It takes 20 seconds for Ball B to make a full rotation.
Find the least common multiple of 20 and 30 to find the time at which they'll meet.
Multiples of 20: {20,40,60}
Multiples of 30: {30,60}
60 is the least common multiple of both 20 and 30.
The balls will meet again at
60 seconds.