I think a but not sure but i hope i helped :D
Answer:
It will take about half an hour more for maria to finish his/her project than Juan.
Step-by-step explanation:
9/10 > 2/6
=> 54/60 > 20/60
=> 34/60
Therefore, it will take about half an hour more for maria to finish his/her project than Juan.
Hoped this helped.