I have the following position

ABC 500 shares @ $120.00

ABC is trading at $15.00. $60000 - $7500 = -$52500

ABC did a reverse split 1:5. An 80% decrease in shares. After the split, it is trading at $40.

How do I calculate the updated position based on my existing average price? I know it results in 100 shares but I'm not sure about the price.