If we define an operation "*": a * b = A-B / AB-1, try to find the value of 2 * (- 3 / 5) Such as the title

If we define an operation "*": a * b = A-B / AB-1, try to find the value of 2 * (- 3 / 5) Such as the title

2*(-3/5)=(2-(-3/5))/(-6/5)-1=-13/6-1=-18/6=-3