To solve this problem, we need to determine the quantity of sugar used in a sweet item where the ratio of sugar to flour is given as 3:4, and the quantity of flour is 400g.
- \(\text{Let the quantities of sugar and flour be } 3x \text{ and } 4x \text{ respectively.}\)
- Since we know that 4x (the amount of flour) is 400g, we can set up the equation: \(4x = 400\)
- Solving for \(x\), we get: \(x = \frac{400}{4} = 100\)
- Substitute \(x = 100\) back into the expression for sugar: \(3x = 3 \times 100 = 300 \text{g}\)
Thus, the quantity of sugar used in the sweet item is 300g.
The correct answer is: 300g.