Hi,
Because the angles are equal (38) and both are right triangles, it is assumed that 3x=12. Now you simply divide and get 4.
13u
Hope this helps!!!!!!!!!!!!
Rate of change is the slope of the line.
Slope = change in y over the change in x.
Slope = (7 - -3) / ( -2 -8)
Slope = 10/-10
Slope = -1