College Placement Test

An apartment building contains 12 units consisting of one- and two-bedroom apartments that rent for $360 and $450 per month, respectively. When all units are rented, the total monthly rental is $4,950. What is the number of two-bedroom apartments?

A. 3 B. 4 C. 5 D. 6 E. 7

E. 7 Explanation: Let x stand for one bedroom apt Let y stand for a two bedroom apt Set a systems of equations:

x  y 

12

$

360

x  $

450

y  $

4

,

950

x 

12

 y

Solve for x Substitute for x in second equations 360

(

12

 y ) 

450

y 

4

,

950 Distribution Property 4320



360

y

4320



450



90

y  y

4

, 

4 950

,

950 Subtract 4320 from each side of the equation 90

y 

630 Combine like terms

y 

7 Divide each side of the equation by 90