Is this equation completely balanced? 2c8h8 + 25o2 8co2 + 18h2o no, because the number of carbon, hydrogen & oxygen atoms on both sides of the equation are not equal. no, because the number of oxygen atoms on both sides of the equation are not equal. yes, because all of the coefficients are in their lowest whole number ratio. no, because the number of hydrogen atoms on both sides of the equation are not equal. yes, because the number of products is equal to the number of reactants.

So to make it clear let's break the equation down species by species and assess the number of each species on bothe sides of the equation:
                   2C₈H₈  +  25O₂   →   8CO₂ +  18H₂O
LHS:  C - 16                                           RHS:  C - 8
          H - 16                                                     H - 36
          O - 50                                                    O - 34

Thus based on that it is evident that the equation is not quite balanced.  This therefore means a "No, because the number of carbon, hydrogen & oxygen atoms on both sides of the equation are not equal."

The actual balance equation would be C₈H₈  +  10O₂   →   8CO₂ +  4H₂O