reset set border set xtics 5 set ytics 20 set grid set xzeroaxis lt 2 lw 2 set yzeroaxis lt 2 lw 2 set style line 1 lt 3 lw 3 set style line 2 lt 5 lw 3 set style line 3 lt 12 lw 3 set xrange [0:30] set yrange [0:200] f(x)=-0.17*x**2+8.5*x+79 plot f(x) ls 1