Final answer:
The number that should replace the question mark in the equation 5 - 9.5 = 5 + ? is -4.5, as subtraction can be rewritten as adding a negative.
Step-by-step explanation:
To find the number that should replace the question mark in the equation 5 - 9.5 = 5 + ?, we need to apply the rules of subtraction and change it into an addition problem, much like the previous examples: 5 - (+3) = 5 - 3 = 2 and subtract -6 from 2: 2 - (-6) = 2 + 6 = 8. Since subtraction is the same as adding a negative, we can rewrite the equation as:
5 + (-9.5) = 5 + ?
Now it is clear that the equation represents an addition problem where a positive number and a negative number are being added. Remember the rule: When two numbers with opposite signs add, subtract the smaller number from the larger one, and the answer has the sign of the larger number.
Following this rule:
5 + (-9.5) = -4.5
Therefore, the value that replaces the question mark is -4.5.