Answer:Drake equation N=R×fs×fp×ne×f1×fi×fc×L where
R=average rate of star formation
fs=fraction of good stars that have planetary systems
Fp=the fraction of stars with habitable planets
ne=number of planets around these stars within an ecoshell
f1=fraction of those planets where life develops
fi=fraction of living species that develops intelligence
fc=fraction of intelligence species with communication technology
L=lifetime of the communication phase
Explanation:this equation is an argument based probability used to estimate the number of active communicative extra terrestrial civilization in the milky way galaxy.