Final answer:
Upon setting up the equation for the same altitude for Plane A and Plane B and solving for x, the result obtained is 42 seconds, which does not match any of the provided multiple-choice answers, suggesting an issue with the calculation or the understanding of the question.
Step-by-step explanation:
To determine when Plane A and Plane B will have the same altitude, we set up an equation where the altitude of Plane A after x seconds plus its starting altitude equals the altitude of Plane B after x seconds plus its starting altitude.
Altitude of Plane A = 500 + 12x
Altitude of Plane B = 164 + 20x
Set the altitudes equal to each other and solve for x:
500 + 12x = 164 + 20x
20x - 12x = 500 - 164
8x = 336
x = 42
However, the answer of 42 seconds is not one of the provided choices, implying there may have been a miscalculation or a misunderstanding of the question. Double-checking the work or seeking clarification of the question is advisable.