4 correct entries received...
1. Sian Yin's working shows that the question can be solved using "Guess and Check" method. However, it did not fulfil the requirement of the question
2. Jonathan attempted to present the expression (representing the number) in a "number" form. However, we are unable to 'reason' this 'form' out mathematically. He managed to form the expressions to form each side of the equation; however, did not form the equation that is the requirement of the question.
3. Peng Kiang's answer is correct and his working flows. However, he did not describe how he arrived at the 2 expressions. As a result of skipping the steps, one might find it difficult to follow-through and make meaning out from the first step.
4. Jeffrey's working shows the various steps clearly: Defining the numbers (using the variable y), forming the equation and solving it systematically.