Answer:
Kim is younger than 5 years. Kim could 1, 2, 3 or 4 years old.
Step-by-step explanation:
Let Kim's age be z.
From the question, Josh's age can be as represented below;

We're also told that the sum of their ages is less than 31, we can express this as per below;

So let's go ahead and find Kim's age, z;

So Kim is younger than 5 years. Kim could 1, 2, 3 0r 4 years old.