b^-18*(b^5)^3
при b=-2

( B^5)^3 = B^15 B^18 * B^15 = B^-3 = 1/ (B^3 )B = - 2 B^3 = - 8 1 : ( - 8 ) = ( - 1/8 ) = ( - 0,125 )Ответ ( - 0,125)