3/8 = 15/a can someone please explain the steps for me? I have 2 hws due today and Idk how to do this

I think the answer is 15/40

Step-by-step explanation:

So basically this  looks like reducing. So first from the three-eights divide the fifteen by three that is 5. So then multiply 8 by 5 and a is = 40

proof divide 40 by 8

answer: 8

step-by-step explanation: if you add the possibilities 5 different flavor and 3 different sizes 5+3=8