Can you solve this tricky maths challenge problem?

Solution in linked video: • This is one of my all-...
This video includes questions from past UKMT maths challenge papers with the express permission of UK Mathematics Trust. The questions may not be copied or made available elsewhere without the permission of the UK Mathematics Trust except in accordance with their policy on the use of intellectual property which may be found here: bit.ly/UKMTIP
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[@user-kh3iu3fg1h]

I got 64, what is the correct answer?

[@oc1anking956]

64

[@bestagent6667]

bro i dont understand how to work this out, and i got my junior maths challenge tmrw

[@jacobclaassen6565]

consider that the overlap removes an equal amount from both

[@oc1anking956]

@@jacobclaassen6565 yh and even if u couldnt see it u could use algebra as well

[@user-yr3mm2co6w]

sameeeeee

[@splitgeogball]

do you know how long it normally takes to get results on the jmc

[@asparkdeity8717]

Let total area of grey be G, and black for B.
If there is no overlap:
G = 11^2 + 7^2 = 170
B = 9^2 + 5^2 = 106
G - B = 64
Now if we over lap the first grey square with the first black square, notice both squares of their respective colour lose the same area, say X; likewise with the other 2 overlaps, say Y and Z areas lost (ie. X,Y,Z are the areas of the white overlaps)
Now, the total difference is:
G* - B* = (G - (X+Y+Z)) - (B - (X+Y+Z))
= G-B
= 64
I think it’s quite intuitive; it’s a nice fact to know that when u are subtracting 2 numbers and change them both by the same amount, the subtraction value is unchanged.

[@arinray73]

Hi Kevin, do you think JMC this year was very easy and the boundaries will be higher?

[@oc1anking956]

certainly

[@angadbains7125]

64

[@user-nh4qe4eo4r]

64

[@user-nh4qe4eo4r]

Is that correct

[@oc1anking956]

@@user-nh4qe4eo4r 100% correct.