Final Answer:
1) The unknown number is 15.
2) Shyam's number is 15 because when he takes away 3, the result is 12.
Step-by-step explanation:
1) Let's denote the unknown number as x. According to the problem, when Shyam takes away 3 from the number (x - 3), the result is 12. So, the equation can be written as x - 3 = 12. Solving for x, we add 3 to both sides, and we find that the unknown number (x) is 15.
2) Shyam's unknown number is 15 because when he takes away 3 (15 - 3), the result is indeed 12, validating our solution.
This problem demonstrates the use of simple algebraic equations to find an unknown number based on a given relationship. Solving such equations is a fundamental skill in mathematics.