Let speed of boat in still water = x kmph Speed of current = y kmph => Rate upstream = $$(x - y)$$ kmph and Rate downstream = $$(x + y)$$ kmph => $$frac{y}{x + y} = frac{1}{7}$$ => $$7y = x + y$$ => $$x = 6y$$ Again, $$frac{2.75}{x - y} = frac{11}{60}$$ => $$x - y = frac{60 * 2.75}{11}$$ => $$6y - y = 15$$ => $$y = frac{15}{5} = 3$$kmph and $$x = 6 * 3 = 18$$ kmph Thus, rate downstream = 18 + 3 = 21 kmph $$ herefore$$ Distance between points A & B = rate downstream * time = $$21 imes frac{52}{60} = 18.2$$ km