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Finding Correct Numbers For The Boxes
How boxes are placed?
Let's assume a, b, c and d are the correct numbers in the boxes.
So, 4 equations that we get are,
a + b = 8 .....(1)
c - d = 6 .....(2)
a + c = 13 .....(3)
b + d = 8 .....(4)
Subtracting (1) from (3) gives,
c - b = 5 .....(5)
Adding (2) to (4),
c + b = 14 .....(6)
Adding (5) and (6) gives,
2c = 19
c = 9.5
Putting c = 9.5 in (2),
9.5 - d = 6
Hence, d = 3.5
Putting d =3.5 in (4),
b + 3.5 = 8
b = 4.5
Putting b = 4.5 in (1),
a + 4.5 = 8
a = 3.5
So to conclude, a = 3.5, b = 4.5, c = 9.5 and d = 3.5.
