If there are 400 cubic centimeters of a chemical in 1 liter of solution, how many cubic centimeters of water must be added to dilute it to a 25% solution?

Keeping in mind that, in 1 liter, there are 1000 cm³, and that the concentration amount of the chemical for say 25% will be 0.25 of whatever the quantity is, so... we convert the percentage amounts to decimal formats.



so.. whatever "x" and "y" are, we know that 1000 + x = y.

and that 400 + 0x = 0.25y.

thus then