First, identify the locations of the pictures, and fill in the question marks with the buliding numbers from which the pictures were taken.
In RSA (Rivest's office is one of the images), you decrypt a string c by raising it to the d'th power and reducing modulo n. Examining the strings you get as binary numbers and looking at each byte's ASCII value (after zero-filling the left side if needed to get an integral number of bytes), they spell the strings shown below each set of numbers. As confirmation that you are performing this step correctly, c0, d0 and n0 decrypt to the string "Answer".
Here are the three other sets of numbers, and what they decrypt to:
decrypted message: 98292145614711 = "Yellow"
decrypted message: 1399813490 = "Sour"
decrypted message: 1409984002076480594290 = "Lousy Car"
What's Yellow, a Lousy Car, and Sour? A LEMON!
2006 MIT Mystery Hunt