A 65 wt $\%$ Ni-35 wt$\% $Cu alloy is heated to a temperature within the $\alpha+$ liquid-phase region. If the composition of the $\alpha$ phase is 70 wt$\%$ $\mathrm{Ni}$, determine:
(a) The temperature of the alloy
(b) The composition of the liquid phase
(c) The mass fractions of both phases