Sorry for asking this but I am pretty new at javascript I could not find the answer;

How can I use subtract in this situation

This is my output;

 output += '<div class="free-shipping-content"><div class="free-shipping-text">SOMETEXTHERE' + ' ' + IdeaApp.helpers.formatMoney(IdeaCart.totalPrice) + ' ' + mainCurrency + 'MORETEXTHERE<div>MORETEXTHERE</div></div>';

IdeaApp.helpers.formatMoney(IdeaCart.totalPrice) gives me the cart total. I want to subtract that number from 200. How can I do that?

For example, if the cart total is $50, I want to subtract this number from $200 and get the result of $150.