Wait for all the continueWith. Tasks and Actions are used in the example.

wait continueWith

static private Func<int, int, int> count = (count, price) =>
{
    return count * price;
};

private void calcButton_Click(object sender, EventArgs e)
{
    int firstCount, secondCount, thirdCount;
    int price = 0;
    
    /**
     * ... initializing firstCount, secondCount, thirdCount.
     */

    Task<int>[] tasks = new Task<int>[] {
        Task<int>.Factory.StartNew(() => count(firstCount, 60)),
        Task<int>.Factory.StartNew(() => count(secondCount, 80)),
        Task<int>.Factory.StartNew(() => count(thirdCount, 85))
    };
    Task[] addTasks = new Task[tasks.Length];

    for (int i = 0; i < tasks.Length; ++i)
    {
        addTasks[i] = tasks[i].ContinueWith(t => price += t.Result);
    }

    Task.WaitAll(addTasks);
    priceLabel.Text = price.ToString();
}