In Problem 21, how many different paths are there from A to B that go through the

Question:

In Problem 21, how many different paths are there from A to B that go through the point circled in the following lattice?

Problem 21
Consider the grid of points shown at the top of the next column. Suppose that, starting at the point labeled A, you can go one step up or one step to the right at each move. This procedure is continued until the point labeled B is reached.