If twice Reena present age is subtracted from four times her age three years from now, the result is equal to three times her age three years ago. What will be Reena age after one year from now?

Introduction / Context:
This is a classic algebraic age puzzle that involves present, past, and future ages in one statement. The sentence looks complicated, but it is simply describing a relationship between linear expressions of the same unknown age at different times. Questions like this are meant to test whether you can carefully decode the language into an equation and then solve for the present age before answering what the age will be after a given number of years.

Given Data / Assumptions:

• Reena has some unknown present age.
• Four times her age three years from now is considered.
• Twice her present age is subtracted from that quantity.
• The result equals three times her age three years ago.
• We have to find Reena age one year from now.

Concept / Approach:
To solve such a question, define a variable for Reena present age. Then write expressions using this variable for her age three years from now and three years ago. Apply the multipliers indicated by four times, twice, and three times, and then convert the verbal condition into a clear algebraic equation. Once that linear equation is solved, you obtain Reena present age. From there, calculating her age after one year is straightforward. The main challenge is reading the sentence slowly and placing the operations in the correct order.

Step-by-Step Solution:
Step 1: Let Reena present age be x years. Step 2: Her age three years from now will be x + 3 years. Step 3: Four times her age three years from now is 4 × (x + 3). Step 4: Twice her present age is 2x, and this is subtracted from 4 × (x + 3). Step 5: Her age three years ago is x − 3, and three times that is 3 × (x − 3). The condition states 4 × (x + 3) − 2x = 3 × (x − 3). Step 6: Solve this equation to get x = 21 years, so Reena present age is 21 years, and her age after one year will be 22 years.

Verification / Alternative check:
Take Reena present age as 21 years. Three years from now she will be 24; four times that is 96. Twice her present age is 42, and 96 − 42 = 54. Three years ago she was 18 and three times that is also 54. Since both sides match, the equation is satisfied and the present age 21 years is correct. Therefore, one year from now she will be 22 years old, which answers the question correctly.

Why Other Options Are Wrong:
Option 21 yrs: This is her current age, not her age after one year, so it does not answer the final question.
Option 20 yrs: If we assume 20, the equation does not balance, because the computed values on each side differ.
Option 24 yrs: This would correspond to an incorrect present age and fails the relationship when tested.
Option 18 yrs: This is too low; substituting 18 years into the equation does not satisfy the condition.

Common Pitfalls:
Many students misread the order of operations and accidentally treat four times three years from now as adding 12 years instead of multiplying the future age by 4. Another common error is to subtract three years instead of adding or vice versa when dealing with phrases like three years from hence and three years before. To avoid these mistakes, sketch a simple timeline, label the present, past, and future ages, and then attach the multipliers only after you have written those expressions correctly.

Final Answer:
Reena age after one year will be 22 years (that is, option 22 yrs).