This is what I understood from the question:

Let the total weight of Mixture A be = 200.

Given, "A mixture A had 15% cement by weight" => 15/100(200) => 30. -> (equation 1)

We were given, "1/4th of the weight of the Mixture A is from Mixture B"

Which can be, Mixture B = 1/4(200) => 50 -> (equation 2), which is the weight of Mixture B that is given to Mixture A.

Now, also given: "1/4th of the weight of the Mixture A is from Mixture B(equation 2), which was 40% cement by weight and added to mixture A".

So, from the above statement, we can get the exact weight of cement. Which is => 40% of (equation 2) => 40/100(50) => 20. -> (equation 3)

Now, The percent increase from the previous cement(equation 1) to (equation 3).

Which is, ( (30 - 20)/20 ) x 100 => ( 10/20 ) x 100 => 0.5 x 100 => 50. I ended up here!

Don't know what to do next! Any help is much appreciated

Thanks in advance

But according to your solution there is no increase rather it's a decrease in your answer.
i.e. From 30 you got 20
So there's a 33% decrease

Yes yess..😅 i'm actually stuck.. is it just me or the question is really tricky ?

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Great explanation . However, the stem is a little bit odd

Thank you rx10! Completely clear.

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