A certain sum doubles in 3 years under simple interest. In how many years will the sum become 5 times itself?

Explanation

To solve the problem step by step, we will use the concepts of simple interest.

### Step 1: Understand the Problem
We know that a certain sum of money doubles in 3 years under simple interest. We need to find out how many years it will take for the sum to become 5 times itself.

### Step 2: Define Variables
Let the principal amount (initial sum) be \( P \).

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