ClearAll;
$DefaultFont = {"Times-Roman",10};
Needs["Graphics`Graphics`"];
f[t_] = Which[t<=1/20,0,
			  t<=1/10,465(20 t - 1),
			  t<=3/20,465,
			  t<=3/10,310(3 - 10t)];

tri1 = Graphics[{GrayLevel[0.65],Polygon[{{0.05,0},{0.1,0},{0.1,465}}]}];
rect = Graphics[{GrayLevel[0.35],Rectangle[{0.1,0},{0.15,465}]}];
tri2 = Graphics[{GrayLevel[0.65],Polygon[{{0.15,0},{0.3,0},{0.15,465}}]}];
shade = Show[tri1,rect,tri2,AxesLabel->{"t","y"},Axes->True,
		PlotLabel->"Ventricular outflow\n\n        y = f(t)"];
plot = Show[shade,Plot[f[t],{t,0,0.3}]];

Show[GraphicsArray[{{plot}}],PlotLabel->"Figure 8.3"];
{Integrate[0,{t,0,1/20}],
Integrate[465(20 t - 1),{t,1/20,1/10}],
Integrate[465,{t,1/10,3/20}],
Integrate[310(3 - 10t),{t,3/20,3/10}]}