Answer:
21
Explanation:
So, this is what is known as the Fibonacci Sequence. Basically, you add number to its preceding term. For example, 1 + 1 = 2 and so forth.
The equation for Fibonacci Sequences is x
![x_(n) = x_(n-1) + x_(n-2)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/39nxmcuu0yulyo6jz28rf2mtl2y5t8uub3.png)
Please let me know if you have any questions. Hope this helps!
Thanks,
Brady