When working on word problems, one of the trickiest parts can be transforming the words into a math equation you can proceed to solve. A good strategy is to start by listing what numbers we know and what numbers we want.

Know:

Amount of mixture: 40L

Amount of acid in mixture: 35%

Amount of water in mixture: 100% - 35% = 65%

Want:

Total L acid: ? (we'll use the variable A for this)

Total L water: ? (we'll use the variable W for this)

We'll first solve for acid. Since it's 35% of 40L, we know that:

A/40L = 0.35 => A = **14L of acid**

Similarly for water:

W/40L = 0.65 => W = **26L of water**