how many distinct pairs of disjoint non-empty subsets of a are there, the union of which is all of a?

What are the five categories of my plate

Which statements about the two fossil images are correct? 1. cave bears are ancestors of plateosaurus. 2. plateosaurus were present on earth before ostracoderms. 3. ostracoderms were the first to die. 4. plateosaurus died after the ostracoderms. 5. cave bears are the oldest fossils.

The equation 24x2+25x−47ax−2=−8x−3−53ax−2 is true for all values of x≠2a, where a is a constant.what is the value of a? a) -16b) -3c) 3d) 16