How many electrons have a +1/2 spin in the 3d, 4d and 5d orbits combined?

What are the two main ideas of this passage? museum experts feel that museums must change to attract visitors. museum experts care more about the number of visitors than about history. museums that display artworks and exhibits do not make families welcome. museums like colonial williamsburg make learning about the past fun. museums in the united states are different than in other countries.