If I’m not mistaken, the area of the wall is 120cm × 100cm = 12000 cm^2 or 1.2m^2

that person wants to tile it using 20cm^2 tiles

so to cover the area of the wall we’ll have to divide 12000 over 20 which equals 600 tiles. But it says that they’ll need only 30 tiles.

Interestingly enough, had the tiles been square in shape and had a side length of 20cm then their area will equal 400cm^2 and in that case 30 tiles will indeed cover the wall, since 12000 ÷ 400 = 30 tiles.

So am I missing something or is it just a typo?

There’s a difference between ‘square’ and ‘squared’.

Check out the top answer on this site: https://www.quora.com/What-is-the-difference-between-square-and-squared

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Aha, I see. Thank you!

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Hey, can I just ask which one was the correct answer for this question? and if i may ask about which resource this is? Thank you in advance

Sure! the correct answer choice is D. As for the file, I was actually sent it by email from the international help desk of the university of Bologna upon inquiring about something else entirely, but I guess it was helpful nevertheless. Though I’m pretty sure I stumbled upon it elsewhere, I think it might’ve been the Cambridge website. I’ll see if I can attach it to you through a reply. If not, I can send it over Gmail.