Answer:
[tex]Time \ in\ school = \frac{3}{8} \ of \ the \ day[/tex]
= [tex]\frac{3}{8} \times 24 = 9 \ hours \ in \ school[/tex]
[tex]Time \ in \ class = \frac{2}{3} \ of \ the \ time \ in \ school = \frac{2}{3} \times 9 = 6 \ hours \ in \ class[/tex]
1 hour = 60 minutes
Therefore, 6 hours = 360 minutes
So , 360 minutes they spent doing mathematics.