Hi,
Please use the hint below.
1. For domain move from left to right and find the minimum value of x-coordinate let us say a, then find the maximum value of x-coordinate let us say b.
Therefore the domain will be [a, b]. If you compare with the question then m = a and x = b.
2. For range move from down to up and find the minimum value of y-coordinate let us say c, then find the maximum value of y-coordinate let us say d.
Therefore the range will be [c, d]. If you compare with the question then n = c and y= b.
Bests,
Rahul