In a chemistry class, 3 liters of a 4% silver iodine solution must be mixed with a 10% solution to get a 6% solution. How many liters of the 10% solution are needed?
Equation: .10x + .04(3-x) = .06(3)
Why is 3-x = .4???
and also why does the 3 multiple with the .6?
Can someone explain this, I don't see why this formula should be set up like this?
Your equation seems wrong.
If $x$ are the liters of the $10$% solution we have the equation: $$ 0.04\times 3 +0.1 \times x = 0.06(3+x) $$