Bicycle meeting calculation

Dan and Johnny live 4 km from each other. They agreed to meet on the way between the two homes. Dan went out at 2 p.m. at a speed of 5 km/h. Johnny rode towards him on a bicycle at 15 km/h. What time did they meet, and how far did John travel?

Result

t = 14:12 hh:mm
s₂ =  3 km

Step-by-step explanation:

$$\begin{gathered} v_1=5\text{km/h} \\ {v}_2=15\text{km/h} \\ s=4\text{km} \\ {s}_1+s_2=s \\ {v}_1\cdot x+v_2\cdot x=s \\ 5\cdot x+15\cdot x=4 \\ 20x=4 \\ x=\frac{4}{20}=0.2 \\ x=\frac{1}{5}=0.2 \\ t=14+x=14+0.2=14.2=14:12\text{hh}:\text{mm} \end{gathered}$$

$s_2=v_2\cdot x=15\cdot 0.2=3\text{km}$

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