Final answer:
The length of the third small table is 2.7 meters.
Step-by-step explanation:
To find the length of the third table, we need to subtract the sum of the lengths of the first two tables from the total length of the long table. Using the given information, we can calculate:
Total length of the long table - (Length of the first table + Length of the second table) = Length of the third table
7.8 meters - (3.5 meters + 1.6 meters) = Length of the third table
7.8 meters - 5.1 meters = Length of the third table
The length of the third small table is 2.7 meters.