Answer: 5.
Step-by-step explanation: Originally, Robert had 9 golf balls. Then, he gave 4 to Tim, so that gives us an immediate clue that this is subtraction. We can solve this problem by the following:
9 - 4 = ?
9 minus 4 equals 5, so we can fill in the question mark with our answer:
9 - 4 = 5.
Therefore, your answer is 5.
Have a great day! :)
