Can you help me with this math

Simplify. (-2)^-3 a. -8 b. -1/8 c. 1/8 d. 8

He weights of 2-pound bags of best dog food are approximately normally distributed with a given mean  and standard deviation  according to the empirical rule, what percentage of the bags will have weights within 3 standard deviations of the mean? 47.5%68%95%99.7%

Which of the following constants can be added to x2 - 3x to form a perfect square trinomial?