#### Answer

We have $10$ milliliters of solution with $34\%$ of concentration, and $90$ milliliters of solution having $4\%$ concentration.

#### Work Step by Step

Let us assume x milliliters of solution 1 must be mixed with y milliliters of solution 2 in order to obtain 100 milliliters solution with 7% of silver nitrate concentration.
So, the equation becomes
$ x+y=100$
Now, consider the concentration of silver nitrate in solution 1 as 34% and in solution 2 as 4%;
And show the total amount of silver nitrate in the mixture as:
$\frac{34}{100}x+\frac{4}{100}y $
We get that the mixture has 7% of silver nitrate, hence the equation becomes:
$\begin{align}
& \frac{34}{100}x+\frac{4}{100}y=\frac{7}{100}\times 100 \\
& 34x+4y=700
\end{align}$
From the equation, we have:
$x+y=100$,
$ y=100-x $
Put $ y=100-x $ in the equation $34x+4y=700$ as given below:
$\begin{align}
& 34x+4\left( 100-x \right)=700 \\
& 34x+400-4x=700 \\
& 30x=300 \\
& x=10
\end{align}$
Therefore, use $ y=100-x $, to obtain the value of y.
$\begin{align}
& y=100-10 \\
& =90
\end{align}$
Hence, we have $10$ milliliters of solution with $34\%$ of concentration, and $90$ milliliters of solution having $4\%$ concentration.