Final answer:
The youngest sibling's age can be found by representing it as Kay den's age and setting up an equation using the sum of their ages. Solving the equation will give us the age of the youngest sibling.
Step-by-step explanation:
Let's call the youngest sibling's age Kay den's age as mentioned in the question. Since the ages of the siblings are consecutive integers, we can represent them as Kay den's age, Kay den's age + 1, Kay den's age + 2, and Kay den's age + 3.
According to the given information, the sum of their ages is 90. So, we can write the equation as:
Kay den's age + (Kay den's age + 1) + (Kay den's age + 2) + (Kay den's age + 3) = 90
Simplifying the equation, we get:
4(Kay den's age) + 6 = 90
Subtracting 6 from both sides, we have:
4(Kay den's age) = 84
Dividing both sides by 4, we get:
Kay den's age = 21
Therefore, Kay den's age is 21 years.