increasing 20 to 40 is the same as increasing 20 by 20 (or itself), so it is a 100% increase. Decreasing 40 to 20 is the same as decreasing 40 by 1/2 or by 20. So it is a 50% increase.
when going from 20 to 40, the number is being doubled, and when youre going from 40 to 20 you are cutting the number in half.
openup 1 em We want to find the points on the curve y=2x^3-3x^2-12x+20y where the tangent line is parallel to the xx-axis, which means that the slope=0
