$(t,y)$ $\Delta t$ $\phi(t,y)$ $\Delta y=\phi(t,y)\Delta t$ $(t+\Delta t,y+\Delta y)$
$(0,0)$ $0.2$ $0$ $0$ $(0.2,0)$
$(0.2,0)$ $0.2$ $0.2$ $0.04$ $(0.4,0.04)$
$(0.4,0.04)$ $0.2$ $0.3984$ $0.07968$ $(0.6,0.11968)$
$(0.6,0.11968)$ $0.2$ $0.58\ldots$ $0.117\ldots$ $(0.6,0.11968)$
$(0.8,0.236\ldots)$ $0.2$ $0.743\ldots$ $0.148\ldots$ $(1.0,0.385\ldots$