1. The problem asks to write a conditional expression in JavaScript that checks if variable $a$ is equal to 5 or variable $b$ is equal to 10. 2. In JavaScript, the equality operator is `==` or `===` (strict equality). Here, we can use `===` for exact match. 3. The logical OR operator is `||` which returns true if either condition is true. 4. So, the conditional expression inside the if statement should be: ```js a === 5 || b === 10 ``` 5. This means if $a$ equals 5 or $b$ equals 10, the condition is met and the message "Condition met" will be logged. Final answer: ```js if (a === 5 || b === 10) {console.log("Condition met");} ```