Answer:
4 : 1
Explanation:
(3 days : 18 hours) this is a ratio , where both the units must be same before simplifying.
1 day = 24 hours, 3 days = (3 × 24) hours
3 days = 72 hours
Now both the units are same, so we can easily simplify now.
72 hours : 18 hours
36 : 9 = 12 : 3
= 4 : 1 ( Answer)