设40元的售出x张,则50元的售出x张,30元的售出200-x-x=200-2x张,由题意得:
30×(200-2x)+40x+50x=7800,
6000-60x+40x+50x=7800,
30x=7800-6000,
x=1800÷30,
x=60;
30元的有:200-2×60=80(张).
答:30元的售出80张,40元的售出60张,50元的售出60张.