Final answer:
To complete the pairs and have a difference of 3, add 4 to both sides of the equation.
Step-by-step explanation:
To complete the pairs and have a difference of 3, the first number of the pair should be the larger number.
So, the equation ? - 4 = 3 can be solved by adding 4 to both sides of the equation.
? - 4 + 4 = 3 + 4
? = 7