Question

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?

Answer 1

Answer:

9 Model As.

Step-by-step 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!