Answer :
the number: n
opposite number: -n
twice the opposite number: 2·(-n)=-2n
27 greater then -2n: -2n+27
n = -2n + 27
n + 2n = 27
3n = 27
3·n = 3·9
n = 9
opposite number: -n
twice the opposite number: 2·(-n)=-2n
27 greater then -2n: -2n+27
n = -2n + 27
n + 2n = 27
3n = 27
3·n = 3·9
n = 9