Please help.....I need a step by step answer/explanation.....

Question

It costs $10 to make earphones, and the start-up costs for manufacturing are $5,000. How many earphones must be produced to get to a cost per unit of $20?

a. 100
b. 30
c. 200
d. 500

Answer 1

5000+10x = 20x

Answer 2

I’m still confused :/