ANSWER: The next three terms in the sequence 5, 10, 20, 40 are 80, 160, and 320.
EXPLANATION: This sequence appears to be a sequence of powers of two, where each term is double the previous term. This means that the next three terms in the sequence will be 2^6 = 64, 2^7 = 128, and 2^8 = 256. This sequence can be written as 5, 10, 20, 40, 80, 160, 320, 640, 1280, 2560, ... and so on.