The position of the jewel in the center of the cross has changed.

For example: 13 gems from top to bottom, the fifth gem is the center of the cross, and the number on the left is also thirteen, which proves that there are seven gems on the left. After the change, if the center of the cross is located at the sixth gem, it is enough to ensure that the number on the left is 13 gem, and it is enough to have six gems on the left, and the same is true on the right, one for each province.

Property 1

Adding (or subtracting) the same algebraic expression on both sides of the equation still holds.

If a=b

Then a+c=b+c

Attribute 2

When both sides of the equation are multiplied or divided by the same non-zero algebraic expression, the equation still holds.

If a=b

Then there is a c = b c

Or a÷c=b÷c (c≠0).