A 10% acid solution and a 70% acid solution are used to make 15 liters of a 50% acid solution.How many liters of the 70% acid solution are u

Let's see GL

Call the amount of 10% solution x.....then the amount of 70% solution is just 15-x....so we have

.10x + .70(15 - x)  = .50(15)

.10x + 10.5 - .70x = 7.5     subtract 10.5 from each side

-.60x  = -3    divide both sides by -.60

x = 5L  that's the amount of the 10% solution

And 15 - x  = 10L     and that's the amount of the 70% solution

Just as GL predicted!!!

For this problem, we need to get to a 50% ratio first, and go from there. To do this, we have to combine 70% and 10% and then take the average of those to see if it reaches 50%.

The way I found it was just to test every combination, and eventually I found a mixture of two parts 70% solution and one part 10% solution gave us 3 parts of a 50% solution. So now that we have our ratios, we can solve.

$${\frac{{\mathtt{1}}}{{\mathtt{3}}}}{\mathtt{\,\times\,}}\left({\mathtt{15}}\right) = {\mathtt{5}}$$

So 5 liters of 10% solution was used.

$${\frac{{\mathtt{2}}}{{\mathtt{3}}}}{\mathtt{\,\times\,}}\left({\mathtt{15}}\right) = {\mathtt{10}}$$

And 10 liters of 70% solution was used.