Suppose y₁(0)=0.6, y₂(0)=0.2, y₃(0)=0.2
Plot y₁(t), y₂(t), and y₃(t) on the same plot for 0 ≤ t ≤ 20, using blue color for the graph of y₁, red color for the graph of y₂, and green color for the graph of y₃.