Answer:
9.072
Explanation:
For this problem, we will simply use the property of 0 and addition to accumulate a sum.
Note, any digit not shown to the right of a decimal can be written with a zero. So 5.9 can be rewritten as 5.900.
Let's perform the addition.
5.900
+ 3.172
-----------
9.072
Using the idea of zeros to the right of the decimal, we are able to trivially complete this sum.
Hence, the answer is 9.072.
Cheers.