Rob Williams - Orangejack

Okay, who knows their math well? I'm trying to figure out how much water ended up in my truck after the hurricane. Here's the measurements of the triangle of water: 6.5 inches deep, 67 inches long, 54 inches wide.

So how many inches of rain did it catch? If you know, post the answer in the comment. I'm curious...and can't remember the formulas.