u print 24k words using 2 sizes of type xl=900w/p sm=1200w/p,u have to use21 pages how many need to be small?

Question

printer prints 24000 words using 2 sizes of type, large type =900 word per page, small type =1200 words per page u have 21pages to use, how many have to be small type, whats the equation?

Answer 1

You can rewrite this into 2 equations:
24000 = 900x + 1200y
x + y = 21

1.) Multiply equation #2 by 900:
24000 = 900x + 1200y
900x + 900y = 18900

3.) Subtract equation 2 from 1:
24000 - 18900 = 900x - 900x + 1200y - 900y
5100 = 300y
y = 17

4.) Plug y into equation 2.
x + y = 21
x + 17 = 21
x = 4

Answer: 4 pages of large type, 17 pages of small type.

Check:
4 * 900 + 17 * 1200 = 24000
3600 + 20400 = 24000
24000 = 24000