Marina correctly simplified the expression Start Fraction negative 4 a Superscript negative 2 Baseline b Superscript 4 Baseline Over 8 a Superscript negative 6 Baseline b Superscript negative 3 Baseline End Fraction, assuming that a not-equals 0, b not-equals 0. Her simplified expression is below. Negative one-half a Superscript 4 Baseline b Superscript empty box What exponent should Marina use for b? mc027-4.j pg m c 0 27-5. j p g 1 7