15/( 15+ 105+x)=( 1/2)* 15/( 15+ 105)
The solution is x= 120.
Add 120g water.
Question 2: 30 coins, consisting of 2 cents and 5 cents, are worth 9.99 cents. How many 2 cents are there? How many are there at five?
Let's have 2 cents x coins, and 9 cents is 99 cents.
2x+5(30-x)=99
x=7
Seven dimes and twenty-three nickels.
Question 3: A can of coke is more than a can of fruit milk, 0.5 yuan. How many tins of coke and fruit milk did you buy? I want fruit milk and coke. 1 listen to coke and 3 yuan money. Here you are, 3 yuan.
Question 4: The teacher leads everyone to play in the park. Aunt Wang, a staff member, said, "You can rent a boat of 13. I'll send you across the river only after you figure out how many boats and boats there are. " Every 5 yuan rents a boat, and every 6 yuan rents a big boat. There are 42 of us. The first little question: all the students want to cross the river. Can you help them figure it out if you are smart? The second small problem: the students were about to board the boat when Chang Fei, the "star of wisdom", suddenly said, "We can only rent 12 boat to cross the river and save money." Is she right? Write down her plan. The third small question: After listening to Chang Fei's plan, the teacher smiled and said, "We can also rent a boat with 1 1, which will save more money!" Can you explain it to everyone for the teacher?
Rent X ship, 13-x ship.
5x+6( 13-x)=42
x=5
There are five small boats and eight big boats.