Determine how many days t will the two isotopes have the same activity

Answer:
t = 1 ... one day
Step-by-step explanation:
3 x [tex]10^{18}[/tex] * [tex](.5)^{t}[/tex] = 6 x [tex]10^{18}[/tex] * [tex](.5)^{2t}[/tex]
3 x [tex]10^{18}[/tex] = [tex](.5)^{2t}[/tex] / [tex](.5)^{t}[/tex]
6 x [tex]10^{18}[/tex]
1/2 = [tex].5^{t}[/tex]
ln( 1/2) = t ln( [tex].5[/tex] )
t = ln( .5)/ln( [tex].5[/tex] )
t = 1