If y = f(x) is transformed to y = -4f(-6x - 15) + 15
then y=-4f(-6(x+5/2))+15.
You see that the x-axis is compressed by a factor of 6, therefore, the point x=6 becomes the point x=1.
Then it is translated by 5/2 to the left, and the point x=1 becomes the point x=-3/2.
The function is scaled by a factor of 4 in y so the point y=-10 goes to y=-40.
It is reflected (factor of -1) with respect to x-axis so the point y=-10 goes to y=40.
It is translated of 15 unit upwards so the point y=40 goes to y=55.
(6,-10) -->*(-3/2,55)