Answer:
S=64
Step-by-step explanation:
if the s is what your looking for
Answer: second option.
Step-by-step explanation:
You must apply 
Then, given the right triangle and the angle D, the opposite side and the hypotenuse of the triangle are the following:

Therefore, when you substitute values, you have:

Reduce the fraction, then you obtain:

Answer:
7 × 8
Step-by-step explanation:
7 number of students × 8 books each student has 7 × 8 = 56