Exponential and Logarithmic Equations

Good Morning,

My problem is: Use a calculator with a y^x key or ^ key to solve the following.

The 1986 explosion at Chernobyl nuclear power plant in the former Soviet Union sent about 1000 kilograms of radioactive cesium-137 into the atmosphere. The functon f(x)=1000(0.5)^ x over 30 describes the amount, f(x), in kilograms of cesium-137 remaining in Chernobyl x years after 1986. If even 100 kilograms of cesium-137 remain in Chernobyls atmosphere, the area is considered unsafe for human habitation. Find f(80) and determine if Chernobyl will be safe for human habitation by 2066.