Answer:
3 days
Step-by-step 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 <u>lowest common multiple</u> of 1 and 3.
L.C.M of 1 and 3=3
Therefore, in 3 days time, she will water them all again.