so you want

pemdas
do 9-2 firtst
9-2=7
now we have

exponents

=3 times 3 times 3=27

=49
now we have
27-5(6-2(49))
do iner parenthasees multiplication
2(49)=98
now we have
27-5(6-98)
inner parenthasees
27-5(-92)
distribute (a(b+c)=ab+ac)
27-(-460)
27+460=487