How much water should we add to 20 kg of seawater to change its concentration from 3% to 2%?

me plz

Aball is dropped from a height of 10m above the ground. it bounce to 90% of its previous height on each bounce. what is the approximate height that the ball bounce to the fourth bounce?

Jim had 15 minutes to do 5 laps around his school what would his time be

Kerion has a beaded necklace business. she can make 12 necklaces is 2 hours. how long will it take her to make 9 necklaces?