They could have assembled total 336 different possible crews.
Step-by-step explanation
Total number of trained pilots is 9 and geologists is 4.
The crew should be consisted of 2 pilots and 1 geologist. That means, 2 pilots are chosen from total 9 and 1 geologist is chosen from total 4.
Number of ways for choosing 2 pilots from 9
and
Number of ways for choosing 1 geologist from 4
![=^4C_(1)= 4](https://img.qammunity.org/2019/formulas/mathematics/college/j7kxs7io69n3nu04v2su8e3s73ze4ajwjh.png)
So, the total possible number of different crews they could have assembled
![=84*4= 336](https://img.qammunity.org/2019/formulas/mathematics/college/ebndjjidrjdfp862chevfs9pmnczheto85.png)