How to get a line plot

i need 3 lines in my graph. one of them is a straight line parallel to x axis at y=200 from x=25 to 45. im not able to get the line

x=[25,32,45]
y1= (20.*3.*1000)./300
plot(x,y1,Color='black',Marker='.')
axis([20 50 100 400])

Answer 1

[Chunru]

x=[25 45];
y=[200 200]

y = 1×2

200 200

plot(x,y,Color='black')
axis([20 50 100 400])

[B!nd]

thanks!