Numbers on iPad

I have an existing spreadsheet created in Numbers on an iPad.

I need to sort alphabetically to find items in a long list.

When I sort, the calculations are messed up - as either, or both, of the formula row and its reference rows can be resorted.

I tried using the preserve rows and columns checkboxes in each formula, but it doesn’t help.

I put together an example spreadsheet to reproduce the situation.

In it, a restaurant is looking at the costs of goods, and whether to make or buy items, a cost comparison.

Please can you recommend to me how I should edit the spreadsheet so I can sort by items alphabetically?

thank you

mich