Answer:
73.72
Step-by-step explanation:
For this subtraction problem, the answer or solution is expressed to the least precise of the numbers we are trying to subtract.
The least precise number is the number with the lowest significant numbers:
105.4 - 31.681
105.4 has 4 significant numbers
31.681 has 5 significant numbers
So;
105.4
- 31.681
------------------
73.719
----------------
The solution is therefore 73.72