def payment(info_list):
    """
    Calculate the payment by the hours and payment per hour.

    :param info_list: list, formed by tuple with hours and payment.
    :return: int, payment calculated by the information of the payment list.

    Usage::
        >>> payment([(3, 50)])
        150
        >>> payment([(2,40), (3, 50)])
        230
    """
    return sum(hours * payment_per_hour for (hours, payment_per_hour) in info_list)