Question 1124077

Company A charges a fee of 3$ plus $0.60 per page.  Company B charges $0.75 per page. How many pages does the book need for company A to cost less than company B? 

I completely forgot how to do this since this is a review from last year, please reply asap with steps including because I want to understand the process.
<pre>Let the number of pages be P
Then for company A, we get cost of: .6P + 3
For Company B, we get cost of .75P
Since Company A needs to cost less than Company B, we have the following INEQUALITY: .6P + 3 < .75P
.6P - .75P < - 3
- .15P < - 3
Number of pages for Company A to cost less than Company B: {{{highlight_green(matrix(1,7, P, ">", (- 3)/(- .15), or, P, ">", 20))}}} <===== INEQUALITY sign changes when dividing by a NEGATIVE value.  
P being greater than 20 means that the number of pages is: {{{highlight_green(21)}}}