DRDO Multi tasking staff Model paper 8

Tips & Tricks
Let acid in the mixture = 7x
And water in the mixture = 3x
And water in the mixture = 3x
According to the question
⇒ 7x/(3x + 4) = 7/4
⇒ 28x = 21x + 28
⇒ 7x = 28
⇒ x = 4
∴ The quantity of acid in the mixture = 7x = 7 × 4 = 28