What is the output of ::: int a = 10; System.out.println(((a++)++)++)));

Question

do explain the reason too.

Answer 1

error
with these
variable
value

mean
a++ return 10
so
(((10)++)++)
(with 10 is value not variable)

Answer 2

Error, because after the first evaluation, that is the inner (a++) evaluates to 10 , you will have the second evaluation, 10++.
The operator ++ expects always a variable, and that ist why the error.

Answer 3

What is the output?

int a = 10;
System.out.println(a--*a--);