## Task 2 - 160522

Two young pioneers in their rowing boat covered a distance of $1 \mathrm{~km}$ and $200 \mathrm{~m}$ downstream in 10 minutes.

How much time did they need to row the same distance upstream, if they covered on average $40 \mathrm{~m}$ less per minute than on the way downstream?
On the way there, the pioneers covered a distance of $1200 \mathrm{~m}$ in 10 minutes, thus on average $120 \mathrm{~m}$ per minute. On the return trip, they covered $120-40=80$ and therefore $80 \mathrm{~m}$ per minute.

Because $1200 : 80=15$, they therefore needed 15 minutes for the return trip.