a. 2
b. 4
c. 10
d. 20
![a 2 b 4 c 10 d 20 class=](https://us-static.z-dn.net/files/dc1/c6ac659e8b19b1ed98f6dd356a2bd236.png)
Answer:
I believe the answer would be 10, just have a good feeling about it.
Step-by-step explanation: