How to SOLVE FOR B from given equation

This is a logistic function. and how would i solve for B in this equation? steps please?
(5,90) so t=5

90= 150/(1+180e^(-b*t)) <-- (b times t)

thanks!!!!

Multiply both sides by (1+180e^(-5b)) so you have 90+16200e^(-5b) = 150

16200e^(-5b)=60

e^(-5b)=3/810

ln(e^-5b)=ln(3/810)

-5b=ln(3/810)

b=ln(3/810)/-5

b=1.119684

90= 150/(1+180e^(-b*t))
9= 15/(1+180e^(-b*t))
(1+180e^(-b*t)) =15/9=5/3
180e^(-b*t) =2/3
e^(-b*t) =120
t=5
e^(-b*5) =120
-b^5=ln(120)
-b= ln(24) Notice - turns it upside down
b=1/ln(24)