How do you calculate return on investment for Guillermo furniture store, which figures do you use in the budget

The short-cut ROI is net income/assets.

However, there's also an extended equation used a lot:
net income/sales x sales/assets
That gets you profit margin, asset turnover and ROI.

Different sources can have variations on these equations. If you are doing this for homework, you need to use the equation you were given.

As for the figures to use, I don't know who Guillermo is, and even if I did and could find something on them, you haven't said what year you're doing... so I don't know what information you even have. I can only give you the equation.