Question 2. Practicing walking every day helps us maintain good health to study, work, and prevent illnesses. Scientists say that each teenager needs to regularly walk 6 000 steps every day. Mary does many things to practice walking every day: - Moving around in the school: 700 steps. - Moving around in the house: 200 steps. - Walking upstairs and downstairs: 200 steps. - Going around on the streets: 400 steps. a)How many further steps does Mary need to walk to reach 6 000 steps every day? b)To reach enough 6 000 steps, besides the above-mentioned activities, every day Mary needs to spend time walking in a park near her house. Mary walks with the speed of 1,2 m/s; the length of her walking step is 0,4m. How many minutes does Mary need to spend walking in the park every day? nhanh nhanh giúp em ạ