1a

public boolean conflictsWith(Appointment other)
{
    if (getTime().overlapsWith(other.getTime()))
    {
        return true;
    }
    else 
    {
        return false;
    }
    
}

2a

public double purchasePrice()
{
    double purchasePrice;
    rate = 1 + taxRate;
    purchasePrice = getListPrice * rate;
    return purchasePrice;
}

3a

public int compareCustomer(Customer other){
    int nameCompare = getName().compareTo(other.getName());
    if (nameCompare != 0) 
    {
     return 1;
    }
    else 
    {
     return getID() - other.getID();
    } 
   }