The given series is mix of two series: 5, 10, 20, ..........and 6, 12, 24, ................
The pattern of first series:
5 x 2 = 10
10 x 2 = 20
20 x 2 = 40
and so on.
The pattern of second series:
6 x 2 = 12
12 x 2 = 24
24 x 2 = 48
and so on.
Thus, next term is 24.