The answer is 89.050 becuase
The rule of adding for sig figs is that since 4.337 has 3 digits after the decimal point, the sum has to have 3 digits after the decimal point also.
So, we can disregard the last 8 and we get 89.049. Now, we round it and since 8>5, and 9>5, the final answer is 89.050.
Here's a good video that really helps: https://www.youtube.com/watch?v=l2yuDvwYq5g
(Please watch it! It's really really helpful! You should start the video at 13:00 because that's where it talks about addition)
I hope this helped you, guest!
If you have any questions, don't hesitate to ask!