Sam needs a 20% acid solution, but she has only an 18% solution and a 25% solution. She decides to use 100 ml of the 18% solution, and she needs to know how much of the 25% solution she should add.
The equation
18+0.25x
= 0.2 represents this situation, where x represents the milliliters of the 25% solution that
100+x
should be added.
How many milliliters should Sam add?
Enter your answer as a number, like this: 42