Question

72-(63-8) and (72-63)-8

Answer 1

They are not equal because for each you get different answer.

$72-(63-8) \\ 72-55 \\ 17$

$(72-63)-8 \\ 9-8 \\ 1$

17 and 1 are not equal.

Therefore, the two expressions  72-(63-8) and (72-63)-8 are not equal .

Answer 2

The Priority is always to parenthesis. It means that in both equations, begin by operating what's inside the parenthesis. Then Subtract what's left.

For the first one you get:
$72 - (63-8)$
$72 - 55$
$17$

For the second one you get:
$(72-63)-8$
$9-8$
$1$

Which mean that The 2 equations are not equal, because $17 \ \textgreater \ 1$
Hope this Helps! :D