Please help solve and explain how rotation works.

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.

The system of equations graphed below has how many solutions? y = 2x + 2

Find the solution of this system of equation -7x+y=-20 9x-3y=36