So I would do this problem by dividing 165 copies by 3 minutes and 45 seconds; that's finding how many 3 minutes and 45 seconds go into 165, and results in how many copies are made in a minute.
Since 3 minutes and 45 seconds is in reality, 3 3/4 minutes, as there are 60 seconds in a minute, I would divide by 3 3/4, or 3.75.
165 / 3.75 = 44
So therefore, a copy machine makes 44 copies per minute.
So 7 x = x2 -18 so you get the quadratic x^2 -7x -18 and then get 2 x -9= -18 and 2 + -9 = -7 so you get (x + 2) ( x - 9) so the positive solution would be x-9 = 0 so x= 9. Hope this helps :)
