A locomotive accelerates a train of identical railway carts. The carts are numbered consecutively with the cart next to locomotive having the number 1. The tension in the connection between the carts with numbers 4 and 5 is three times begger than the tension in the connection between the carts with numbers 14 and 15. What is the number of the last cart? there is no resistance to the train's motion.

Explanation

To solve the problem, we need to analyze the situation involving the tensions between the railway carts and how they relate to the number of carts.

### Step-by-Step Solution:

1. **Understanding the Problem**:
- We have a locomotive pulling a series of identical railway carts.
- The carts are numbered consecutively, starting from 1 next to the locomotive.
- The tension between carts 4 and 5 is three times the tension between carts 14 and 15.
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