Algebra 1 Help!?

Question

The pages of a book are 15 cm by 20 cm. Margins of equal width surround the printing on each page and comprise one half the area of the page. Find the width of the margins.

My answer is 10 inches, but I don't think I'm correct...

What do you think? Please show your work in EQUATIONS THAT FACTOR!

Thanks for helping me!

Oops, I'm sorry about that typo... My answer was 10 cm... Not 10 inches... Sorry!

Answer 1

why 10 inches as we are using cm?

page = 15 x 20 = 300 cm^2
and one half this area 150 = margin area

so now we need to determine how much to shrink the page space
so that we have 150 cms of interior space - by shrinking
the height and width by the SAME amount

so interior page is 150 hmmmmmmmm
already using 15 x 20

so let's try 10 x 15

ooooo gives us 150 interior sq cm
reduces each dimension by 5 cm divided by 2 = margins

margins are 2.5 cm each side

TA DAAAAAAAAAA!

brilliant!

almost
need the calculations - huh?
x = 2 margins
(15 - x) (20 - x) = 150
300 - 35x +x^2 = 150
x^2 - 35x + 150 = 0
(x-5)(x-30) = 0

x can be 5 or 30
divide both by 2
2.5 or 15 - and 15 is toooooooo much
answer is 2.5

BRILLIANT!!!!

I need to go to bed - bye !