Respuesta :

Answer:

17

Step-by-step explanation:

  1. 38 - 21 = 17
  2. 21 - 4 = 17
  3. The difference between each pair of numbers above is 17, so that is the common difference.

I hope this helps!

Answer:

common difference = 2nd term - first term = 21-4=17

Step-by-step explanation: