[tex]dane:\\s_1 = s_2 = s\\v_1 = 6\frac{km}{h}\\t_1 = 20 \ min\\v_2 = v_1 - 2\frac{km}{h} = 6\frac{km}{h}-2\frac{km}{h} = 4\frac{km}{h}\\szukane:\\t_2 = ?\\\\Rozwiazanie\\\\s = v\cdot t\\\\s = v_1\cdot t_1\\oraz\\s = v_2\cdot t_2\\\\v_2\cdot t_2 = v_1\cdot t_1 \ \ /:v_2\\\\t_2 = \frac{v_1}{v_2}\cdot t_1\\\\t_2 = \frac{6\frac{km}{h}}{4\frac{km}{h}}\cdot20 \ min\\\\\underline{t_2 = 30 \ min}\\\\Odp. \ a)[/tex]
