{[(107-63:x)*9-2]:5+27}*4-12=800
{[(107-63:x)*9-2]:5+27}*4=800+12
{[(107-63:x)*9-2]:5+27}*4=812
[(107-63:x)*9-2]:5+27=812:4
[(107-63:x)*9-2]:5+27=203
[(107-63:x)*9-2]:5=203-27
[(107-63:x)*9-2]:5=176
(107-63:x)*9-2=176*5
(107-63:x)*9-2=880
(107-63:x)*9=882
107-63:x=882:9
107-63:x=98
63:x=107-98
63:x=9
x=63:9
x=7