Question

Из пункта А и Б выехали одновременно навстречу друг другу мотоцикл и велосипедист. Они встретились на расстоянии 4 км от Б,а в момент прибытия мотоциклиста в Б велосипедист находился на расстоянии 15 км от А. Найти расстояние от А до Б.

Answer 1

X-скорость мотоциклиста
y-скорость велосипедиста. Во сколько раз скорость мотоциклиста больше скорости велосипедиста, во столько раз путь одного больше пути другого. Составим две пропорции
$\frac{x}{y} = \frac{S-4}{4}$
$\frac{x}{y} = \frac{4}{S-19}$
$\frac{S-4}{4}= \frac{4}{S-19}$
S^2-23S+60=0
S=20 или 3(по смыслу не подходит). Вот я так рассуждала

Answer 2

Problem Analysis

We are given that a motorcycle and a cyclist start from points A and B simultaneously and meet at a distance of 4 km from point B. At the moment the motorcycle arrives at point B, the cyclist is 15 km away from point A. We need to find the distance between points A and B.

Solution

Let's assume the distance between points A and B is x km.

When the motorcycle reaches point B, the cyclist is 15 km away from point A. This means that the motorcycle traveled x km, while the cyclist traveled (x - 15) km.

When they meet, the total distance traveled by both the motorcycle and the cyclist is equal to the distance between points A and B, which is x km. Therefore, we can set up the following equation:

x + (x - 15) = x

Simplifying the equation, we get:

2x - 15 = x

Bringing the x term to one side, we have:

2x - x = 15

Simplifying further, we get:

x = 15

Therefore, the distance between points A and B is 15 km.

Answer

The distance between points A and B is 15 km.