Fe3+ (aq) + SCN- (aq) <> Fe(SCN)2+ (aq) K = 8.9x10^2 at 298 K. A reaction mixture at 298 K initially contains 0.100 M Fe(SCN)2+, 0.100 M Fe3+ and 0.150 M HCN-. Find the equilibrium concentrations of each of the reactants and products.
Can someone explain the break down a bit more, and how 0.25x comes into play? I'm not familiar with the quadratic equation so more detail would be appreciated.

Fe3 aq SCN aq ltgt FeSCN2 aq K 89x102 at 298 K A reaction mixture at 298 K initially contains 0100 M FeSCN2 0100 M Fe3 and 0150 M HCN Find the equilibrium conce class=