Solve the problem in the picture.

See below

Step-by-step explanation:

Recall that

and the identity , therefore

because will always be .

Thus,

Now considering the Absorption Law,

Once , therefore

we know

Answer-

Kai spends 8 hours 20 minutes in school.

Solution-

Let us assume, Kai spends x minutes in school.

Kai calculates that he spends 15% of a school day in science class and that is 75 minutes, i.e

Therefore, Kai spends 8 hours 20 minutes in school.