You can use a diffrent kind of ruler for math then you could find the answer.
20✔️3 + 4✔️27
20✔️3 + 4✔️9 • 3
20✔️3 + 4 • 3 ✔️3
20✔️3 + 12✔️3
32✔️3.
The solution is 32✔️3.
Using the Pythagorean theorem, the diagonal measure is found as
√((18 m)² +(24 m)²) = √(324 +576) m = √900 m
= 30 m
You would be swimming 30 meters.