As of 2019, the New York Yankees had won the World Series more than any other team in baseball. The difference of the number of World Series championships won by the Yankees and 2 times the number of World Series championships won by the second-most-winning team, the St. Louis Cardinals, is 5. The sum of the two teams' World Series championships is 38. a. Write a system of equations to find the number of World Series championships won by the Yankees, y, and the number of World Series championships won by the Cardinals, x.

From the details of the number of World Series won by the Yankees and the St. Louis Cardinals we are given, we can write the following system of equations to find the number of World Series championships won by the Yankees, 'y', and the number of World Series championships won by the Cardinals, 'x' as follows;

y - 2·x = 5...(1)

y + x = 38...(2)

2) Making 'y' the subject of both equations gives;

For equation (1)

y = 5 + 2·x

For equation (2)

y = 38 - x

Equating both 'y' values gives;

y = 5 + 2·x = 38 - x

2·x + x = 38 - 5

3·x = 33

∴ x = 33/3 = 11

The number of World Series championships won by the St, Louis Cardinals, x = 11 World Series championships

From y = 38 - x, we have;

y = 38 - x

∴ y = 38 - 11 = 27

Therefore, the number of World Series championships won by the Yankees, y = 27 World Series championships