Question 304126
1.) B = 0.20(100,000 - T )
2.) T = 0.40(100,000 - B)

You have two equations in two unknowns to solve simultaneously.

Rewrite 1.) as

3.) B = 20000 - .2*T 

and 2.) as

4.) T = 40000 - .4*B

Substitute (20000 - .2*T) from 3.) in 4.) and solve for T:

T = 40000 - .4*(20000 - .2*T)
T = 40000 - 8000 + .08*T
T - .08*T = 32000
.92*T = 3200
T = 3200/.92

T = ?

Take the value for T above and substitute in 3.) to calculate B.