Question 596435
You made one silly error and I'm going to highlight it in red.


(-1/20)x^3 - (2/12)x^2 <font color="red">-</font>(2/25)x + (4/15) 


It's very small, but hopefully you can see that the negative in front of 2/25 is highlighted in red. This should be a + because -2/5 and -1/5x are both negative (that multiply out to a positive result), so the real answer is



(-1/20)x^3 - (2/12)x^2 + (2/25)x + 4/15