\( 7 x \) when \( x=3 \)

When you substitute \( x = 3 \) into the expression \( 7x \), you get \( 7 \times 3 \) which equals 21. So, \( 7x \) becomes 21, making this a quick and fun way to simplify and calculate expressions using algebraic variables. This example showcases the beauty of algebra, where solving for \( x \) can reveal interesting insights into patterns. You can experiment with other values of \( x \) to see how the results change. Just remember, the more you practice substituting values, the easier it will get!