The average wages of a worker during a fortnight comprising 15 consecutive working days was Rs.90 per day. During the first 7 days, his average wages was Rs.87/day and the average wages during the last 7 days was Rs.92 /day. What was his wage on the 8th day?

Explanation:-

The total wages earned during the 15 days that the worker worked ,
= 15 * 90 = Rs. 1350.
The total wages earned during the first 7 days = 7 * 87 = Rs. 609.
The total wages earned during the last 7 days = 7 * 92 = Rs. 644.

Total wages earned during the 15 days,
= wages during first 7 days + wage on 8^th day + wages during the last 7 days.

1350 = 609 + wage on 8th day + 644.
wage on 8th day = 1350 - 609 - 644 = Rs. 97.