“…Fractional differential equations (FDEs) have gained importance due to their numerous applications in various fields of science and engineering, such as physics, biophysics, blood flow phenomena, aerodynamics, electro magnetic, fluid flow, diffusive transport akin to diffusion, chemistry, electron-analytical chemistry, electro dynamics of complex medium, polymer rheology, viscoelasticity, control, porous media, probability, electrical networks, biology, etc. For details, see [13,17,18,28,31,33,37,39,44]. Many researchers have studied the existence of solutions for nonlinear FDEs with different tools such as fixed-point theorems, the topological degree theory, and the method of upper and lower solutions, for instance, see [5,6,20].…”