How to subtract mixed numbers

The difference of 2 numbers is 21 and the quotient of the equation is 4 then what are the two numbers?

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.

4. bob solved the inequality problem below incorrectly. explain his error and redo the problem showing the correct answer. −2x + 5 < 17 −2x + 5-5 < 17-5 -2x/-2 < 12/-2 x < -6