The number of hours, H, of daylight in Madrid as a function of date is approximated by the formula H=12+2.4sin(0.0172(t−80)),
where t is the number of days since the start of the year. (We can think of t=0 as the stroke of midnight on Dec. 31/Jan 1; thus, January falls between t=0 and t=31, February falls between t=31 and t=59, etc.).

Find the average number of hours of daylight in Madrid (assuming in each case that it is not a leap year):