A titration was done on a 25.00 mL a liquot of Naott. The endpoint of the 3.00 M H, PO4 solution occurred at 28. 35 mL . What was the molarity

Hello, I need help understanding the first part of this problem? I am confused as to where the coefficient 3 for NaOH came from and the coefficient for H(OH) too. Also, can you explain where (-) (+), and (-3) exponents came from and why do I need this to solve the equation? Is this balancing an equation?

A titration was done on a 25.00 mL a liquot of Naott.The endpoint of the 3.00 M H, PO4 solution occurredat 28. 35 mL . What was the molarity concentrationof the aliquot of NaoH ?`Molarity of the aliquot of NaOH =M Na off* Where did thesecome from ?NQOHA HE* ( POAND Na , POA $3 / H (OH)Lo" where did this "13 ")LD where did thiscome from ?"13 " come from ?