Challenge: fix the broken sales report

This report has three problems. One is a number stored as text, one is a range that starts a row too low, and one is a figure typed in where a formula should be. Everything you need to find them is in Parts 1 to 12.

The third fault is the interesting one, because right now it is displaying exactly the right number. A hardcoded value is not wrong until the data changes, and then it is wrong silently, forever, and nobody checks it because it was right last time they looked.