How many more barrels of gasoline then diesel were produced last year

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.

How long must $542 be invested at a rate of 7% to earn $303.52 in interest? in a easier way

How many quarts of a 50% solution of acid must be added to 20 quarts of a 20% solution of acid in order to get a 40% solution of acid?