How to simplify the expression by combining like terms

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%

F(x)=5/6x+3 which of the following is true

A6 ounce bottle of dressing costs $1.56 a 14 ounce bottle costs $3.36 a 20 ounce bottle costs $5.60 which has the lowest cost per ounce