1. Analyze the Question
The goal is to find a single, unique value for the ratio `m/n`. This is a Data Sufficiency question, so we need to know if it’s possible to find one, not what the value is.
2. Analyze Statement (1)
• “If m is decreased by 3 the ratio of m to n becomes 3 : 10.”
• This gives us a clear, unambiguous equation: `(m - 3) / n = 3 / 10`.
• This is a single equation with two variables (`10m - 3n = 30`). We cannot find a unique ratio from one equation.
• Conclusion: INSUFFICIENT.
3. Analyze Statement (2)
• “If m + n is increased by 3 the ratio of m to n becomes 7 to 12.”
• We must take this wording literally. The phrase “m + n is increased by 3” is the key. It tells us that the sum of the two variables changes, but it does not specify how that change is distributed between `m` and `n`.
• For example, does this mean:
• `m` increases by 3 and `n` is unchanged? The equation would be `(m + 3) / n = 7 / 12`.
• `n` increases by 3 and `m` is unchanged? The equation would be `m / (n + 3) = 7 / 12`.
• `m` increases by 1 and `n` increases by 2? The equation would be `(m + 1) / (n + 2) = 7 / 12`.
• Since there are infinite ways to change `m` and `n` so that their sum increases by 3, this statement does not provide a single, unique equation.
• Conclusion: INSUFFICIENT.
4. Combine Both Statements
• We have one clear equation from Statement (1): `10m - 3n = 30`.
• However, Statement (2) is ambiguous and does not provide a second clear equation.
• Since we cannot form a consistent system of two equations, we cannot find a unique solution for `m` and `n`. Depending on how we interpret the ambiguous second statement, we would get a different answer for the ratio `m/n`.
• Because we cannot find a single, unique ratio, the combination is not sufficient.
• Conclusion: INSUFFICIENT.
The final answer is E.