Im never good with these, anyone know what it is

Which statements regarding efg are true? check all that apply.

What is the value of x when x + 7 = 21?

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%