270oC
230oC
250oC
200oC
Δl1 = Δl2lα1ΔT1 = lα2ΔT2α1/α2 = ΔT2/ΔT14/3 = (T - 30)/(180 - 30)4/3 = (T - 30)/1504 * 150 = 3 * (T - 30)600 = 3T - 90690 = 3TT = 230°C