How do you plan to solve it?
module jk_ff_enable ( input CLK, input EN, input J, input K, output reg Q ); always @(posedge CLK) begin if (EN) begin case ({J, K}) 2'b00: Q <= Q; 2'b01: Q <= 1'b0; 2'b10: Q <= 1'b1; 2'b11: Q <= ~Q; endcase end end endmodule