I don't get it.

How to use order of operation in 20 divide by 4 multiply 5 = 1

Table which ratio is equivalent to 3: 7? 6: 7 3: 21 24: 56 15: 30

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%