Hi there!
We can first see how much money he has already earned. He earns $8 dollars every time he walks the dog and has already walked the dog 5 times. This means he has gotten $8 5 times, giving us 8 * 5, or 8 + 8 + 8 + 8 + 8, which is equal to 40.
Now, we know he wants $88 in total. We know he has earned $40 already, so he only the remaining portion after that left. We want to see how much that is, so subtract 40 from 88 to get $48 left to earn.
Now, we know he earns $8 dollars each time he walks the dog, and he wants $48 more. Thus, we are looking for how many times $8 fits into $48 to see how many more times he needs to walk the dog to earn this $8. This can be done by dividing 48 by 8, to get 6 more times.
Thus, your final answer is he needs to walk the dog 6 more times to earn enough money to buy a game that costs $88.
Hope this helps!