In Roman Numeration, the symbol X can be subtracted from ____, M and C only.
L
Step 1: Know the values.
\(X = 10\)
\(L = 50\)
\(C = 100\)
\(M = 1000\)
Step 2: Learn the subtraction rule.
Only \(I, X, C\) can be placed before a larger symbol to subtract.
Each one can be subtracted from only the next one or two larger symbols:
\(I\) from \(V\) or \(X\)
\(X\) from \(L\) or \(C\)
\(C\) from \(D\) or \(M\)
Step 3: Apply the rule to \(X\).
\(X\) can come before \(L\) to make \(XL = 40\)
\(X\) can come before \(C\) to make \(XC = 90\)
Step 4: What about \(M\)?
\(X\) is not placed before \(M\). “\(XM\)” is not a valid Roman numeral.
Step 5: Fill the blank.
So \(X\) can be subtracted from \(L\) and \(C\) (not from \(M\)).
The blank should be: \(L\).
Note: The phrase in the question including \(M\) is likely a typo. The standard rule is “\(X\) can be subtracted from \(L\) and \(C\) only.”