In this paper, we investigate a class of fractional equations with nonlinear boundary condition. We establish a new comparison principle related to linear fractional equation and show the existence of extreme solution by using monotone iterative method and lower and upper solutions method.

![Some remarks on [Carpathian J. Math. 39 (2023), No 2, 541--551]](https://www.carpathian.cunbm.utcluj.ro/wp-content/uploads/carpathian_2024_40_3_623_626_001-400x400.png)

