q1 = heat to raise temperature of ice from -16.5 C to zero C.
q1 = mass ice x specific heat ice x (Tfinal-Tinitial)
q2 = heat to melt the ice.
q2 = mass melted ice x heat fusion
q3 = heat to raise temperature of melted ice from zero C to final T.
q3 = mass melted ice x specific heat water x (Tfinal-Tinitial)
q4 = heat released by warm water at 84.5 C when lowered to final T.
q4 = mass warm water x specific heat H2O x (Tfinal-Tinitial)
Substitute for each of the above and set to zero as
q1 + q2 + q3 = 0
and solve for Tfinal.
Post your work if you get stuck.