How to solve error Cannot implicitly convert type 'decimal?' to 'decimal'?

Error: Cannot implicitly convert type 'decimal?' to 'decimal'.An explicit conversion exists (are you missing a cast?)

public Nullable<decimal> SRP;
public decimal Total;
Total = PurchaseOrder.SRP* PurchaseOrder.Quantity;


Solution:
I added Value in SRP
Total = PurchaseOrder.SRP.Value * PurchaseOrder.Quantity;