Answer:
109.0
Explanation:
When adding or subtracting values, you must round your answer to the same "place" as the measurement with its last significant figure furthest to the left.
That is, you round off to the same number of decimal places as the measurement with the fewest decimal places.
43.0
50.0
+16.0
109.0
In each measurement, the “0” is the significant figure furthest to the left, so you round off the number to the “tenths" place. That's the last column that the measurements share.
109.0 → 109.0 (rounded to the “tenths” place)
In other words, you do not round off, and the sum has four significant figures.