I am working on the antioxidant activity of some plant extracts. I obtained a linear graph but i don't know how to calculate the IC50 value from the plot. The equation of the graph for Ethylacetate fraction is: Y = 54.745x - 0.3653, R2 = 1. While the equation of the graph for aqueous fraction is: Y = 24.323x + 24.325; R2 = 0.9988. Please, find the attached for the graph. Thank you.