Find the nearest unabridged dictionary. Your library will have one if your classroom does not (or even if your classroom does). Look up these words. The dictionary will have a good definition, and will tell you whence they came. These words have been around for a while.
There is an on-line dictionary here, which has definitions and etymology of minuend and subtrahend.
In brief, a subtraction problem is
minuend - subtrahend = difference
There is an on-line dictionary here, which has definitions and etymology of minuend and subtrahend.
In brief, a subtraction problem is
minuend - subtrahend = difference