A certain lightbulb has a tungsten filament with a resistance of 19 when cold and 140

Question:

A certain lightbulb has a tungsten filament with a resistance of 19Ω when cold and 140 Ω when hot. Assume that Equation 17.7 can be used over the large temperature range involved here, and find the temperature of the filament when it is hot. Assume an initial temperature of 20°C.