Verified Answer :

20868

your answer is -542,340

2  {390 - [ 5 ( 10 - 4 / 2)] + 15} 2.
2
{390-[5(8)]+15}2
2{390-[40]+15}2
2{390[-40]+15}2
2 {-135,585}2
{-271170}*2
-542,340

so PEMDAS

the order of simplification/operation is
parenthaseese
exponents
multiplication or division whichever comes first
addition or subtraction whichever comes first


so we work the parenthasees inside to out

inside parenthaseese=(10-4/2)
so no exponents so skip
there's division so we do that
4/2=2/1=2
then we have
(10-2)
subtraction
10-2=8
(8)
next parenthaseese/bracket
[5 times (8)+15]
multiplication
5 times 8=40
[40]
other brackets
{390-[40]+15}
subtraction
390-40=350
{350+15}
350+15=365
outside
2 times {365} times 2
multiplication
2 times 365=730
730 times 2=1460