Guys I need help on number 19 and 20.

One-third of the people from country a claim that they are from country b, and the rest admit they are from country a. one-fourth of the people from country claim that they are from country a, and the rest admit they are from country b. in a combined census of the two countries, one-half of the total claimed to be from a. what is the ratio of the populations of country a to that of country b.

Officer brimberry wrote 24 tickets for traffic violations last week, but only 9 tickets this week. what is the percent decrease? give your answer to the nearest tenth of a percent.

Diane owes $387 to her brother. if she debits her bank account $161.25 a month to pay him back, how many months will it take her to pay off the debt?