Answer:
Subtraction.
Step-by-step explanation:
We are asked to determine the name of operation that is used for given terms: less than, minus, difference, reduced, decreased by, diminished by.
We can see that all the given terms show that some quantity is being taken away from them. We know that when we take some quantity from another quantity, this means we are using subtraction.
Therefore, the name of the operation that defines the given terms is "subtraction".
