Hey there!
Write a proportion. 8/5=32/x. Cross multiply. You get 8x=160. You have to isolate x, so divide each side by 8. X=20. Since x is by itself, you have your answer. The answer is B. Another way to do this is to see how much it takes to get from 8 to 32. You would multiply by 4. So multiply 5 by 4 to get 20.
I hope this helps!