Final answer:
The correct answer is option B) 5. To solve for X in X - 2 = 7, we add 2 to both sides, leading us to X = 9. The number to put in the green box is 5 because adding it to 2 must equal 7.
Step-by-step explanation:
The correct answer is option B) 5.
To solve the equation X - 2 = 7, we need to isolate the variable X on one side of the equation. This is done by doing the same thing to both sides of the equation, which in this case means adding 2 to both sides. By adding 2 to the left-hand side, the -2 and +2 cancel each other out, leaving us with X on the left.
Therefore, when we add 2 to the right-hand side (7 + 2), we get 9, which is X's value. However, we are looking for the number to enter into the green box which follows a similar logic. The green box plus 2 should equal 7. Thus, the green box should contain the number 5 because 5 + 2 = 7.
When solving equations, it's critical to perform the same operation on both sides to maintain the equality. This is a fundamental principle in algebra that enables us to find the value of the unknown variable.
It is also important to check the answer to ensure it makes sense. In this case, substituting 5 for the green box indeed gives us a true statement: 5 + 2 = 7.
To solve the equation X-2 = 7 + [?], we want to isolate the variable X on one side of the equation. To do that, we need to cancel out the -2 on the left side. Since -2 and 7 are constants, we can add 2 to both sides of the equation.
So, X - 2 + 2 = 7 + 2 becomes X = 9.
Therefore, the number that belongs in the green box is 5.