What subway do you take to get to 50th Street and eighth Avenue from Penn Station?

Take the Uptown A-C-E* (the blue line) or the Uptown 1-2-3 (the red line), one stop, from 34th Street-Penn Station to 42nd Street-Times Square.

Transfer at Times Square to the S shuttle train, east across 42nd Street, from Times Square (West 42nd) to Grand Central Station (East 42nd).

Transfer at Grand Central to the Uptown 6 train (of the 4-5-6, the dark green line). Take the Uptown 6 trainone stop to 51st Street.

You will exit the subway at 51st Street and Lexington Avenue. From there, it's just one block north, and three avenue blocks east to 52nd and 1st Avenue: Lexington Avenue ---> 3rd Avenue ---> 2nd Avenue ---> 1st Avenue.

You will be able to tell which way is north/south/east/west because you will exit the subway on the east side of Lexington Avenue. The west side of the street is the Downtown side, and the east side of the street is the Uptown side.