Board Game Arena

Hi successfully played 7 Wonders Architect with a family member who uses a tablet.
Hit a snag on 2nd game when constructing Wonder. If you need 3 of the same resources for the next part of the Wonder and have 2 stone, 2 bricks and get a gold coin how do you proceed to construct the next part of your Wonder?

It gives you the option of which of the two resources to use with the gold coin.

Thanks Tomkoch - difficulties overcome.