2.75 mi+3 mi+ 2.5 mi =?

Why did the ice arena get so hot after the big game (this is math related google it to find the paper

Im gonna fail 7th grade selective breeding 1. creates offspring which are genetically identical to the parent 2. is the process of breeding only organisms with desirable traits 3. involves the removal of the nucleus of a cell 4. combines traits from organisms of different species

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