*NO ALGEBRA SOLUTION:* There is one solution with 10% sugar and another solution with x% sugar, which when combined give you 16% sugar

This is a very simple question and while generally people use algebra for mixtures questions, I would advise to STAY AWAY FROM ANY ALGEBRA and use a simpler method:

If 1/4th of the 10% solution is replaced, that means only 3/4th of the final mixture is the 10% solution (S1) and 1/4th is the x% solution (S2).

Therefore we can say that the two solutions S1 and S2 are mixed IN THE RATIO 3 : 1

S1____________S2

10%__________

x%_______

16%______

__

3a____:____

1a__

Now, we need to find the actual value in which the solutions were mixed. To get the value of this, you need to subtract Solution 1 from the middle value and Solution 2 from the middle value. Then, you take the absolute value of the resulting numbers to give you 1a and 3a.

So

1a = 10 - 16 = 6

3a = x - 16

If 1a = 6, 3a is therefore = 18.

Now, x% - 16% = 18, therefore x% = 34. Answer is B.

As a note: This method can be difficult to grasp in the beginning but once you are able to understand it, you will never use any other method to solve mixtures questions.
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