PROBLEM WITH RECURSIVE CONVOLUTION

question about recursive convolution If I had this system: y[n]-0.8y[n-1]=2x[n]

and an input x[n]= δ and a initial condition y[-1]=a I need the signal output of the convolution y[n] in recursive mode when n>=0 and n<0 and plot when n[-4 4] but i dont know how to do it any help is welcome. Thank you so much