Given that Angelo's kayak travels 10km/h in still water, and the river's current flows at a rate of 4km/h.
Travelling downstream means Angelo is travelling with the current, that is the current of the water will add to Angelo's speed.
Their combined speed will be;
[tex]\begin{gathered} v=10\text{ km/h + 4 km/h} \\ v=\text{ 14 km/h} \end{gathered}[/tex]To travel 35 km downstream;
[tex]\text{distance = 35km}[/tex]Recall that;
[tex]\begin{gathered} \text{speed = }\frac{\text{ distance}}{\text{time}} \\ \text{time = }\frac{\text{ distance}}{\text{ speed}} \end{gathered}[/tex]substituting the given values;
[tex]\begin{gathered} \text{time = }\frac{35\operatorname{km}}{14\text{ km/h}} \\ \text{time =2.5 hours} \end{gathered}[/tex]Therefore, it'll take 2.5 hours
[tex]undefined[/tex]