SOLUTION: One day, an electronics store ships 4 identical laptop computers and 5 identical monitors, for a combined weight of 60 pounds. Another day, it ships 2 laptop computers and 4 monit

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: One day, an electronics store ships 4 identical laptop computers and 5 identical monitors, for a combined weight of 60 pounds. Another day, it ships 2 laptop computers and 4 monit      Log On


   

Question 1135202: One day, an electronics store ships 4 identical laptop computers and 5 identical monitors, for a combined weight of 60 pounds. Another day, it ships 2 laptop computers and 4 monitors, for a combined weight of 42 pounds. What is the weight of one laptop and the weight of one monitor?
Answer by ikleyn(52914) About Me  (Show Source):
You can put this solution on YOUR website!
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4x + 5y = 60    pounds    (1)

2x + 4y = 42    pounds    (2)



To solve this system, multiply eq(2) by 2 (both sides).  Keep eq(1) as is.  You get


4x + 5y = 60              (3)     (same as (1) )

4x + 8y = 84              (4)


Now subtract eq(3) from eq(4) (ELIMINATION method !).  You get


     3y = 24  =================>  y = 24/3 = 8 pounds is the weight of one (of each) monitor.   ANSWER


Then from eq(1)  x = %2842-4%2A8%29%2F2 = 5  pounds is the weight of one (of each) computer.    ANSWER

Solved.

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On the way,  you learned on how the ELIMINATION method works.