Answer:
Alexa: 58.8%
Benito: 12.5%
Carmen: 28.7%
Explanation:
(70m + 15m + 35m)x=5000
x=41.67 times
41x120m=4920m, leaving 80 m which Alexa and Benito got an extra time.
Alexa painted 42 times
Benito painted 41.67 times
Carmen painted 41 times
Alexa: 42x70m=2940m, 2940/5000=58.8%
Benito: 41.67x15m=625m, 625/5000=12.5%
Carmen: 41x35m=1435m, 1435=/5000=28.7%