[ ( 6 x - 72 ) : 2 - 84 ] . 28 = 5628
[ ( 6 x - 72 ) : 2 - 84 ] = 5628 : 28
[ ( 6 x - 72 ) : 2 - 84 ] = 201
[ ( 6 x - 49 ) : 2 - 84 ] = 201
[ ( 6 x - 49 ) - 84 ] = 201 . 2
[ ( 6 x - 49 ) - 84 ] = 402
( 6 x - 49 ) = 402 + 84
( 6 x - 49 ) = 486
6 x = 486 + 49
6 x = 535
x = 535 : 6
x = 84