Why are there numbers by the subject sorry im new

Janet is mixing a 15% glucose solution with a 35% glucose solution. this mixture produces 35 liters of a 19% glucose solution. how many liters of the 15% solution is januet using in the mixture? a. 25 liters c. 28 liters b. 7 liters d. 10 liters

The highest point on earth is the peak of mount everest if you climb to the top you would be approximately 29,035 feet above sea level at remembering that amount is 5280 feet percentage of the height of the mountain would you have to climb to reach a point 2 miles above sea level

When you answer this can you explain