Deepti went to school for 216 days in a full year. If her attendance is 90%, find the number of days on which the school was opened.
Sonal went to school for 219 days in a full year. If her attendance is 75%. Find the number of days on which the school was open.
A boy attends school for 'r' days in a month. The number of days he is absent in a month is two more than one sixth of the days he attends the school. The mathematical expression for the number of days he remains absent in a month is