For number 3, the answer is the third bubble because you are trying to find the difference between the number and 7 which will equal to 21. So it would be n-7=21. And if you plug n as 28, it would be true because 28-7 indeed equals to 21.
For number 4, the answer would be the first choice because you will need to set up an equation where the price of the pizza and the price of the salad add up to $10 which is the total amount of money that you have spent. So the equation would be 8+s=10
