What multiplies to -18 and adds to -11

What is the difference between regular convex and concave polygons

Can someone me with these two circle theorem questions asap?

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%