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At Elisa's printing company, there are two kinds of printing presses: Model A, which can print 70 books/ day, and model B, which can print 55 books per day. The company owns 14 total printing presses that allow them to print 905 books per day. How many model A presses do they have?

User Matthijn
by
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1 Answer

3 votes

Answer:

9 Model As.

Explanation:

Let A represent Press A and let B represent Press B.

So, they own 14 total presses. This means that:


A+B=14

They can print 905 books per day, in other words, since A prints 70 per day and B prints 55 per day:


70A+55B=905

This is now a system of equations. Solve by substitution. From the first equation, subtract B from both sides:


A=14-B

Substitute this into the second equation: "


70(14-B)+55B=905

First, we can divide everything by 5 to simplify things:


14(14-B)+11B=181

Distribute the left:


196-14B+11B=181

Combine like terms:


-3B+196=181

Subtract 196 from both sides:


-3B=-15

Divide both sides by -3


B=5

So, the company has 5 Model B presses.

Which means that the company has 14-5 or 9 Model A presses.

And we're done!

User Ouwen Huang
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