Resistance of tungsten wire at 150∘C is given as R150=133Ω
⇒‌‌R0(1+αt)=133‌‌[∵Rt=R0(1+αt)]
⇒‌‌R0(1+150α)=133.......(i) Similarly, resistance of wire at 500∘C is given as R500=R0(1+500α) R0(1+500α)=R500.....(ii) From Eqs. (i) and (ii), we get ‌