So hmm the distances are clearly 6km and 15km anyway
so hmmm alrite.. recall your d = rt, or distance = rate * time
if the rate of speed of the tourist's boat is say "r", on the river, against the stream, is not going to be "r" but we have to subtract the river's speed, since we know is "2", thus the speed of the boat is " r - 2"
now, off he goes on the lake, however, the lake is just still water, so, on still water, his speed is indeed just "r"
if he sailed "t" time in the river, on the lake was 1 extra hour, or " t + 1 "
thus
solve for "r"
so hmmm alrite.. recall your d = rt, or distance = rate * time
if the rate of speed of the tourist's boat is say "r", on the river, against the stream, is not going to be "r" but we have to subtract the river's speed, since we know is "2", thus the speed of the boat is " r - 2"
now, off he goes on the lake, however, the lake is just still water, so, on still water, his speed is indeed just "r"
if he sailed "t" time in the river, on the lake was 1 extra hour, or " t + 1 "
thus
solve for "r"