The mean temperature from Monday to Thursday is $$39.25^{\circ}C$$. The mean temperature from Thursday to Sunday is $$40.25^{\circ}C$$. If the sum of the daily temperatures of all the days during the week, from Monday to Sunday, is $$277.5^{\circ}C$$, then what is the temperature for Thursday?

The mean temperature from Monday to Thursday is $$39.25^{\circ}C$$.

total temperature from Monday to Thursday = $$39.25\times4$$ $$^{\circ}C$$

= $$157^{\circ}C$$    Eq.(i)

The mean temperature from Thursday to Sunday is $$40.25^{\circ}C$$.

total temperature from Thursday to Sunday = $$40.25\times4$$ $$^{\circ}C$$

= $$161^{\circ}C$$    Eq.(ii)

If the sum of the daily temperatures of all the days during the week, from Monday to Sunday, is $$277.5^{\circ}C$$.

total temperature from Monday to Sunday = $$277.5^{\circ}C$$    Eq.(iii)

Temperature for Thursday = Eq.(i)+Eq.(ii)-Eq.(iii)

= (157+161-277.5) $$^{\circ}C$$

= (318-277.5) $$^{\circ}C$$

= 40.5 $$^{\circ}C$$