<p>A clerk typed 8 memos, each either 1 or 2 pages long. If the clerk typed 12 pages in all, how many of the memos had 2 pages?</p>
<p>instead of trying to figure it out mathematically I think it might be faster to just do guess and check.</p>
<p>Say ok if I do 5 of the 2-pagers then I get 3 one-pagers which gives me a total of 13 pages. Ok 13 is more than 12 so let’s try one less of the two-pagers. So if I had 4 of the 2-pagers that leaves me with 4 one-pagers and that comes out to be a total of 12…BINGO</p>
<p>4 is the answer</p>
<p>I’s much faster to do it just by looking at the problem and figuring out it’s 4. Here’s the real math though:
let x = # of memos 1 page long, y = # of memos 2 pages long
x + y = 8
1x + 2y = 12</p>
<p>x = 8 - y
(8 - y) + 2y = 12
y = 4</p>