6th grade Q3

An algebraic equation is a mathematical sentence that uses numbers, letters, and symbols, including an equal sign ($=$), to show that two expressions are equal. In the equation $x-10=31$, the letter $x$ is a variable, which represents a number that is not yet known.

Let's explore how to create an algebraic equation in a real-life situation. Imagine you have some marbles, but you don’t know the exact number. Let's say you start with $x$ marbles. Then you add 7 more marbles and count them all, finding that you have 18 marbles in total. This situation can be represented by the equation $x+7=18$, where $x$ represents the number of marbles you started with.

For another example, suppose you have some candies, though you haven't counted them. Let's assume you start with $y$ candies. You then give away 4 candies and count what you have left, which turns out to be 12. This situation can be expressed with the equation $y-4=12$.