A mobile company charges Rs.1.50 per minute during the daytime i.e. from 7:00 am to 11:00 pm and Rs.'x' per
minute during the night i.e. from 11:00 pm to 7:00 am.The total talking time per hour decreases by 50% during the night.Find the value of 'x' if the average amount charged by the mobile company during the whole day is Rs.1.40 per minute.