The average consumption of electricity in a house was 18 units/day for the first x days of August. For the next 3x days the average consumption was 16 units/day. For the next 3x days the average consumption was 1.5 units/day more than the average consumption of the first 4x days and the total consumption of the last 3 days of the month was 78 units. Find the average consumption per day of August.