20 is the next number in the series 38, 36, 30, 28, 22. This is obtained by studying the given series of numbers for patterns since there is no common difference between each number.
The first term of the series is 38, and all subsequent numbers have a difference of two or six. The series is decreasing and not increasing. The last number is 22, and the number before 22 is 28. The difference between them is six. Hence, the next number should have a difference of two. The equation 22 - 2 = 20 provides the next number in the given series of numbers.