How 7%(5//2) = 1 ???

Answer 1

Simple:
5//2=2 and 7%2=1

Answer 2

5//2 is 5/2 without decimal.
5/2 = 2.5
5//2 = 2

7%2=1
In modulo operator you can always subtract or add anything that is dividible by the second operand (2) to the first operand (7).
First operand = 7
Second operand = 2

We can subtract 6 (3*2) from the first operand.
7-6 = 1

The first operand is now 1.
When the first operand is positive, but less than the second operand, the result is the first operand.

That's why 7%2=1.