The big outside purple square above has an area of 84

Did take lil time to figure out the trick to it! The answer is [B]

The trick is to place all the cut sections together and realize that they form a rectangle of 2x*x/ 7 are where x is the side. We already know that x^2 = 84. If we substitute the values we can find that the answer is 24! took me 1:58. I believe this is the shortest way to it

Regards,
Arpan

Yeah it might take 30+ seconds just to see the trick of moving the triangles over, it certainly wasn't obvious to me at first. But the shapes of the three figures hint at how the three shapes interconnect, in particular the one block on its own and the triangular shape missing only one square. Once you put them together the yellow portions fill 2 entire columns out of 7, and if you're familiar with the multiplication table you may quickly identify 84 as being 12 x 7, meaning that you have 2/7 of the table filled, with each 1/7 corresponding to exactly 12 units. Ergo, 24. Good question! It took me about a minute just to see the trick and then 15 seconds from there. Sometimes it's good to spend a little time figuring out the correct way instead of diving into calculating the area of irregular shapes.

Hope this helps!
-Ron

This is easy - with a little experience at pattern recognition!

If you put the regions shaded in yellow together - you will be able to fill up two rows of squares - completely. The area of the shaded region, therefore is 2/7th of 84 or 24 units.

Cheers!

All three yellow pieces when set together will form 2/7 th of the total area which is 84.
So required area =2/7×84
=24
Option B is the answer.

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