Quantity selector not adding to the price

[LaFrenchToile]

Hello everyone. 

As said in the title, I am trying to make it so that when the quantity selector is being used in the product page it also adds up to the price, Here is a screenshot showing what I mean. 

So instead of showing 69.99 it should show 139.98.

I have already tried a code based on this thread (https://community.shopify.com/c/shopify-design/help-with-refresh-theme-refreshing-item-price-on-quan...).

Also tried looking at different other forum post but no solutions has really been found. 

[LaFrenchToile]

Hello, thank you for your reply.

I tried copy and pasting it to my CSS files but it doesn't seems to be working, I am not sure what I am doing wrong as I have no coding experience.