(4) \( 20 \div(-5) \)

When you divide \( 20 \) by \( -5 \), you’re essentially asking how many times \( -5 \) fits into \( 20 \). Since dividing a positive number by a negative number results in a negative number, we find that \( 20 \div (-5) = -4 \). So, the answer is \( -4 \). This mathematical principle is not just a classroom trick; it’s a real-life demonstration of how sometimes models or systems can have opposing forces. Think of a scenario in economics where gaining from one side could mean a loss on another! Understanding this helps in grasping various concepts like profit and loss.