Question30f8(1 point) t o Back ' | Question3 v| | 9 Next ' b1: A radioactive substance decays from 75 mg to 12.75 mg in 20 years according to the exponential decay model 3,! : ae_ , where a is the initial amount and y is the amount remaining aer :1: years. Find the b -Value. Round to the nearest hundredth, If needed. 1:: Use the EXACT bvalue to write the exponential decay model for this substance with initial amount 75 mg, then use that model to nd the half-life. Find the half-life. Round to the nearest hundredth 0ft} year, gf needed. half-life m \\:|years