Question 30677
First, substitute the variables for the numbers:

{{{8000=4000/(1+t)}}}


Next, isolate the variable:

{{{8000(1+t)=4000}}}  
[multiply both sides by (1+t)]


{{{(1+t)=(4000/8000)}}} 
[divide both sides by 8000]


{{{t = (4000/8000)-1}}} 
[subtract 1 from both sides]


Then, simplify:

{{{t = (1/2)-1}}} 
[simplify the fraction]


{{{t = -1/2}}}  
[subtract the numbers]