asanjis printing inc. has two types of printing presses: model a and model b. model a can print 80 books per day and model b can print 60 books per day. altogether asanji has 18 printing presses. if he can print 1260 books in a day, then how many of each press does he have
Let's say asnaji only had model b. That means that 60*18=1080 books are printed in a day. 1260-1080=180. This 180/20 is 9. Asanji has 9 model A and 9 model b. Why we can do this is because we find the least then we find the difference with how many we actually have. This is the difference between the least and what we have.
+57 Here are the things we know about this problem:
Model A can print 80 books per day and Model B can print 60 books per day. (We will use "A" to represent Model A and "B" to represent Model B)
The total number of books printed, or "jobs", is 1260.
There are 18 printing presses.
Using this information, we can come up with an equation.
(80/1)(A) + (60/1)(B) = 1260
...There are two variables that we don't know. But, we do know that there are 18 total printing presses, so we can represent the variable B as (18 - A):
(80)(A) + (60)(18-A) = 1260
Now we just do the math.
(80A) + (-60A + 1080) = 1260
A = 9
Now we can go back and substitute A back in (18 - A) to find B.
18 - 9 = 9, B = 9
I haven't done these rate problems in a while so there's room for mistake, so please correct me if I'm wrong 
