Gabrielle rides her bicycle from home to school. For the first 5 minutes, she rides at a speed of
200 m/min, and then she changes the speed to
300 m/min for next 10 minutes. If she is still 180
m away from school, what is the distance
between Gabrielle's home and school?

Our ancient human ancestors once lived only in Africa, in tiny bands of a few thousand hunter-gatherers. Then we moved out of our African cradle, spreading rapidly to every corner of the planet. How did we acquire the skills, technology and talent to thrive in every environment on earth? How did our prehistoric forebears cross the Sahara on foot, survive frigid ice ages, and sail to remote Pacific islands? “Great Human Odyssey

Explanation: