Answer:
Let x be the amount (in liters) of the 5% acetic acid solution to be added.
Let y be the amount (in liters) of the 10% acetic acid solution to be added.
The system of equations is:
x + y = 2 (the total amount of solution is 2 liters)
0.05x + 0.10y = 0.07(2) (the amount of pure acetic acid in the final solution is 7% of 2 liters)
Simplifying the second equation:
0.05x + 0.10y = 0.14
5x + 10y = 14 (multiplying both sides by 100)
We now have a system of two equations with two variables. We can solve it by substitution or elimination. Here, we'll use substitution:
x + y = 2 => x = 2 - y (subtracting y from both sides)
Substituting x in the second equation:
5(2 - y) + 10y = 14 (replacing x by 2 - y)
10 - 5y + 10y = 14
5y = 4
y = 0.8
So the photographer should add 0.8 liters of the 10% acetic acid solution and 2 - 0.8 = 1.2 liters of the 5% acetic acid solution. We can check that this solution satisfies both equations:
0.05(1.2) + 0.10(0.8) = 0.06 + 0.08 = 0.14
1.2 + 0.8 = 2
Therefore, the answer is:
The photographer should add 0.8 liters of the 10% acetic acid solution and 1.2 liters of the 5% acetic acid solution.