Упростим выражения: 1 ) 6 * а * ( - 2 * b) * ( - c ) = 6 * a * 2 * b * c = 6 * 2 * a* b *c = 12 * a * b * c ; 2 ) - 5 / 6 * а * ( - 4 / 5 * b) * 3 / 8 = 5 / 6 * a * 4 / 5 * b * 3 / 8 = ( 5 * 4 * 3 ) / ( 6 * 5 * 8 ) * a * b = 1 / 2 * 1 / 2 * a * b = 1 / 4 * a * b = 0.25 * a * b ; 3) - 0.5 * а * ( - 7 * b ) * ( - 2 * с ) = - 1 / 2 * a * 7 * b * 2 * c = - 7 * a * b ; 4 ) - 4 * m * 0.8 * с * ( - 5 * d ) = 4 * m * 0.8 * c * 5 * d = 4 * m * 4 * c * d = 16 * m * c * d.