Answer:
3 days
Explanation:
Some of Hannah‘s plants need water every 1 day.
Some need water every third(3) day.
If she waters them all today, we are to determine when next she will waters them all again.
To do this, we find the lowest common multiple of 1 and 3.
L.C.M of 1 and 3=3
Therefore, in 3 days time, she will water them all again.