Caprice adds equations a and b to solve this system of equations. what makes this
approach a valid method in general for solving a system of equations?
equation a: 8x + 3y = 27
equation b: 4x – 3y = 9
12x = 36

According to a study conducted in 2015, 18% of shoppers said that they prefer to buy generic instead of name-brand products. suppose that in a recent sample of 1500 shoppers, 315 stated that they prefer to buy generic instead of name-brand products. at a 5% significance level, can you conclude that the proportion of all shoppers who currently prefer to buy generic instead of name-brand products is higher than .18? use both the p-value and the critical-value approaches.