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

225x²+4=0

225x²=0-4

225x²=-4

x²=-4/225

x=±√-4/225