15 X 18 = 270
270/12 = 22.5
The water rose 22.5 feet and deposited the ark on Mount Ararat?
Okay.
+++++++++++++++
If you will read the verses before your partial rendering, you will find that it was fifteen cubits above the “highest hills”
(Genesis 7:18-20.)
18 And the waters prevailed, and were increased greatly upon the earth; and the ark went upon the face of the waters.
19 And the waters prevailed exceedingly upon the earth; and all the high hills, that were under the whole heaven, were covered.
20 Fifteen cubits upward did the waters prevail; and the mountains were covered.