How to get Shopping Cart SubTotal simply

My shipping plugin not process FreeShippingOverX, product with free shipping in a clean manner.
Exists a shortcut for get the shopping cart subtotal without the headache of treat with applied discounts, taxes, fees etc...?
for ex:
_orderTotalCalculationService.IsFreeShipping(cart, subtotal);
If I understand, with this I can set the shipping method name to "Free Shipping" and rate to 0.00.

Thanks in Advance

(What version of nopCommerce are you using?)

4.30

_orderTotalCalculationService.GetShoppingCartSubTotal(cart,
     includeTax,
    out orderSubTotalDiscountAmount, out orderSubTotalAppliedDiscounts,
    out subTotalWithoutDiscountBase, out subTotalWithDiscountBase);

subTotalWithoutDiscountBase does not include discounts.

Thanks New York,

Sorry 4.30 version, in 4.00, the last version I worked on, I used exactly that.
I'm complicating myself for nothing :-), thank you very much for the reminder!
This time I used much less code for the same result.