Someone pls answer this for me

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

Gabriel determined that his total cost would be represented by 2.5x + 2y – 2. his sister states that the expression should be x + x + 0.5x + y + y – 2. who is correct? explain.

What is the ratio fraction form of 25: 9