Answer:
35 days
Step-by-step explanation:
Andrew brings juice for lunch every 5 days and Hannah brings juice every 7 days
Find the lowest common multiple of 5 and 7
Andrew (every 5 days) = 10, 15, 20, 25, 30, 35, 40, 45, 50
Hannah (every 7 days) = 14, 21, 28, 35, 42, 49, 56
The lowest common multiple of 5 and 7 is 35
Therefore, if Andrew and Hannah both brought juice today, it will take 35 days before they will both bring food again on the same day.