Help please I don’t know the answer

Create a real-life situation and create a system and show how it might be modeled algebraically with a system of equations (or inequalities) show all work include a few sentences explaining the situation, your variables of choice and what each represents, and how you would set it up and solve it algebraically. !

A.s.a.! similarity in right triangles, refer to the figure to complete this proportionc/a = a/? a.) cb.) hc.) rd.) s

What is the missing value in the proportion 4/5 = x/30