Answer:
An exponential function with a growth factor of 1/2 would have 1.5^x as part of it.
The exponential growth function is as follows.
r is the rate of growth (0.50)
The plane went 100 meters higher than its original height
Step-by-step explanation:

I think, he made a mistake because the exponents have different values but then if you'll look at his results, he just wrote the same thing. If you want, you could post the original problem, and I'll solve it for you :)
Can you add a picture? I don't see a circle. I will answer this question if you add a picture.
Sorry this is a tricky one IDK I'll ask some others to help you