“…Many books on fractional differential equations, fractional calculus have been published (see, for example [15,16,18,21,32]), and some recent papers on the topic, see [1,3,4,5,7,9,11,12,14,19,24,25,26,32] and the references therein. At the same time, there are many papers concerned with solvability of coupled systems of nonlinear fractional differential equations, because of their wide applications.…”