Expert: Lynn Houston - 4/29/2009

Question
An Apartment building contains 80 apartments. One bedroom apartments rent for $850 per month. Two-bedroom apartments rent for $1050 per month. The total monthly rental income is $78400. How many apartments of each type are in the building?

Find the equation system and solve.

Answer
let t = 2 bedroom apartments and b = one bedroom apartments.

t + b = 80 and
1050t + 850b = 78400.  

Solve the first equation for t or b (I'll use t)

t = 80-b  (now, substitute the value of t into the second equation)

1050(80-b) + 850b = 78400
84000 - 1050b + 850b = 78400
5600 = 200b
b = 28, therefore t = 52