Final answer:
The missing value in the solution to the equation 6x + 7y = 4x + 4y is not applicable, as the equation represents infinitely many solutions.
Step-by-step explanation:
To find the missing value in the solution to the equation 6x + 7y = 4x + 4y, we need to simplify and isolate either x or y. Let's choose to solve for y:
Combine like terms on both sides: 6x - 4x + 7y - 4y = 0
Simplify: 2x + 3y = 0
This equation represents infinitely many solutions since it's the equation of a straight line. Therefore, there is no missing value in the solution to the equation.