Solving with \( \leqslant \begin{array}{l}\text { Write the following sentence as an equation. Use } \mathrm{x} \text { to represent "a number." } \\ \text { Five times a number yields } 21 \text {. }\end{array} \)

To express "Five times a number yields 21" as an equation, you can write it as \( 5x = 21 \). Here, \( x \) represents the unknown number you're trying to find. It's like saying if you take a mystery number, multiply it by five, and you’ll end up with 21! When solving this equation, remember to isolate \( x \) by dividing both sides by 5. So, you'd write \( x = \frac{21}{5} \). This means your mystery number is 4.2! Common mistakes include forgetting to divide by the same number on both sides or misplacing the equal sign, so double-check those steps for a smooth solve.