Answer:
<h2>Amanda needs 72 grams of paint</h2>Step-by-step explanation:
Notice that she already painted one face of each cube, that is, 8 faces in total, and she used 24 grams for that.
Now, there remain 3 faces per cube to be painted, which means there are 24 faces.
Then, we use the rule of three, if she used 24 grams of paint for 8 faces, how much grams of paint she would need to paint 24 faces?
Therefore, Amanda needs 72 grams of paint for the unpainted surfaces.