What place from this table is chosen at random let even a = the place is a city. what is p(ac)

Will give brainliest if you answer question correct

Given the two similar triangles, how do i find the missing length? if a=4, b=5, and b'=7.5 find a'

I’ve been trying all day to figure this puzzle out. i need the work for it aswell. it is a factoring polynomials tarsia. the image is below.