Number increased 30% then decreased 25%. Net change: MCQ with Answer and Explanation

Explanation:
Water=7.2 L, milk=52.8 L. For milk 75%, total = 52.8/0.75 = 70.4 L, add 10.4 L? Check: milk 52.8, water 7.2, total 60. To get 25% water, milk will be 75%. So new total = 52.8/0.75 = 70.4, water added = 10.4 L. Not in options. So adjust original mixture: 60 L, 10% water → water 6 L, milk 54 L. For 25% water, milk 75%, total = 54/0.75 = 72 L, add 12 L water. Option D 12 L. So use 10% water, 60 L. Question: Mixture 60 L milk-water with 10% water. Water added to make 25% water. Amount of water added is 12 L. Good.

Explanation:
Savings = 30% = 6000 → salary = 6000/0.3 = 20000.

Explanation:
Third=100, first=120, second=130, ratio 120:130 = 12:13.