solving systems by elimination

Question

the apple store sells ipads and Macbooks. ipods cost $200 each, and Macbooks cost $1,200 each. this year, the number of Macbooks they sold was twice the number of ipods they sold. their total sales was $780,000. how many ipods did they sell this year?

Answer 1

Take out the information you need:

ipods are $200

Macbooks are $1,200

Total sales $780,000

 

Make an equation: (I'm choosing the variable "n" to represent the number of ipods sold, but you could pick any letter)

200n + (2n * 1,200) = 780,000

 

Solve:

200n + 2,400n = 780,000

      2,600n      = 780,000

 

Divide both sides by 2,600 to get the variable by itself. 

n = 300

 

Answer:

n is the number of ipods sold, so your answer is 300 ipods. 

 

Check your answer: substitute 300 for n in your equation above. 

(200*300) + (2*300*1,200)

Does it equal 780,00?