Final answer:
The correct expression to determine how much further Emilio ran than Marcus is 10x - 4 - (5x + 2), which simplifies to 5x - 6.
Step-by-step explanation:
The question asks us to write an expression that represents how much further Emilio ran than Marcus. To find out this difference, we subtract Marcus' distance from Emilio's distance. The correct expression for this is option b) 10x - 4 - (5x + 2). When we distribute the subtraction, we need to change the sign of each term within the parentheses. This will give us 10x - 4 - 5x - 2. Combining like terms results in 5x - 6, which is how much further Emilio ran than Marcus expressed as an algebraic expression.