Let's first set the current speed X and the ship speed as A, and then set the whole distance of the lifebuoy falling after B hours of departure as S.

S/(x+a)=6 This is the distance divided by the downstream speed, which is equal to 6 hours. S/(a-x)=8 This is the simultaneous expression of the two upstream equations, and A can be eliminated, so that the relationship between S and X can be obtained easily. S=48x。 Hehe, the result is right? S/x =48 is the distance divided by the speed of the current, which is equal to the time for the ship to travel from place A to place B with the current, which is equal to 48 hours.

The second problem is to list the equation (b/6) * s+(6-b+1) * x = (7/8) * s, and explain this equation to you. Go down the river for 6 hours, take B/6 of the whole journey, and follow the river for the rest of the journey until the ship reaches B, drifting for 6-b hours, and then drifting for 6-b after driving back for an hour. X equals the distance between the lifebuoy and the water ticket. How far is it to the left of the equal sign? It takes eight hours for the boat to go upstream. It takes an hour to walk now. Picking up the lifebuoy is equivalent to walking one-eighth of the whole journey, and then the lifebuoy walks seven-eighths. Ok, now solve this equation. Divide both sides of the equal sign by x, and you will find that the first question S/x is equal to 48. Take it in and get b=5 hours. Hehe, I hope I can help you at last.