[20-2{5+ (-12)} x 2(5-2-9)}]

[20 - 2{5 + (-12)} $\times$ 2(5 - 2 - 9)}]

= [20 - 2{5 - 12} $\times$ 2(5 - 11)}], solving simple brackets first

= [20 - 2{-7} $\times$ 2(-6)}]

= [20 - {-14} $\times$ -12], solving curly brackets

= [20 + 14 $\times$ (-12)]

Now we apply multiply operation before addition as per BODMAS rule,

= [20 - 168], solving square brackets

= -148 (answer)