Final answer:
The equation that represents the situation is a) 50 + 3x = 77.
Step-by-step explanation:
The correct equation to represent the situation is a) 50 + 3x = 77. This equation represents the initial number of homes (50) plus 3 times the number of months (x) equals the total number of homes in the neighborhood (77).
Each month, 3 new homes are built, so we need to multiply the number of months by 3 and add it to the initial number of homes to reach the total number.