I need some help anserwing this question

With #! i’ve tried to figure it out but i can’t.

Each of the four sides of a swimming pool measures 9 meters. the pool is 5 meters deep. how much water will be needed to fill it completely? a. 45 cubic meters b. 81 cubic meters c. 225 cubic meters d. 405 cubic meters reset next

Iwill give ! if m∠a=59 and m∠3=81°, what is m∠b? m∠b= _[blank]_°