Question

Together, two printers can print 7500 lines if the first printer prints for 2 minutes and the second prints for 1 minute. If the first printer prints for 1 minutes and the second prints for 2 minutes, they can print 9000 lines together. Find the number of lines per minute that each printer prints.

My answer:

let first print speed: v1 (limes/min)
second print speed : v2 (lines/min)
2v1+v2 = 7500 lines =>v2 = 7500 - 2v1
v1 + 2v2 = 9000 lines
=> v1 + 2(7500-2v1) = v1 + 15000 - 4v1 = 9000
=> 3v1 = 15000 - 9000 = 2000
=>v1 = 2000 lines/min
v2 = 7500-2*v1 = 7500 - 2*2000 = 3500 lines/min
answer:
first print speed: 2000 lines/min
second print speed: 3500 lines/min

Check please, I'm not too good at word problems!

Answer 1

you did fine

the only thing I would object to is your running of the equal sign across the page.
here is how it should be presented:
v1 + 2v2 = 9000
v1 + 2(7500-2v1) = 900
v1 + 15000 - 4v1 = 9000
7500 = 3v1
v1 = 3500

etc.
each line should contain only one equal sign, it makes it so much easier to read.