Andrew is about to leave for school. If he walks at a speed of 50 meters per minute, he will arrive 3 minutes after the bell rings. If he runs at a speed of 80 meters per minute, he will arrive 3 minutes before the bell rings. In how many minutes will the bell ring?

The answer is: 13 minutes

Step-by-step explanation:

First Let us form equations with the statements in the two scenario

Let the time in which the bell rings be 'x'

1. If Andrew walks (50 meters/minute), he arrives 3 minutes after the bell rings. Therefore the time of arrival at this speed = (3 + x) minutes

2. If Andrew runs (80 meters/minute), he arrives 3 minutes before the bell rings. Therefore the time taken to travel the distance = (x - 3) minutes

In both cases, the same distance is travelled, therefore, equation (1) = equation (2)

Next, collecting like terms:

dividing both sides by 3:

x =  390÷30 = 13

∴ x = 13 minutes

step-by-step explanation:

you can add the two numbers and divide the result by 2. or you can find the gap between the two numbers and add half of this to the smaller number.