The easiest way to understand the answer is to consider two straight lines.
y = 3x + 6
and 2y = 6x + 12
When you graph these two lines, one will be on top of the other. That will give you an infinite number of solutions.
The answer does not depend on the two equations being straight lines. All that is required is that one graph sits on the other. So you could have a pair of quadratics
y = x^2 + 3x + 10
2y = 2x^2 + 6x + 20
would also give you an infinite number of solutions.
If you are multiplying 16 times 2 then 32 would be your answer. If you are subtracted your answer would be 14. If you are adding them your answer would be 18. I don’t really see what sign is being used.
When you square a number, you chose a number and multiplying itself. If you did the square root of 25, you would get 5. However if you divided 25 by 2, you would get 12.5 which is NOT the square root.