1. Stating the problem: Siew Ling gave 40% of her salary to her father. He spent 75% of that amount on food and had 180 left. We need to find Siew Ling's total salary. 2. Let S be Siew Ling's salary. 3. Amount given to father = 40% of S = $0.4S$. 4. The father spent 75% of the amount given on food, so spent $0.75 \times 0.4S = 0.3S$ on food. 5. The amount left with father is the remainder: $0.4S - 0.3S = 0.1S$. 6. This remainder equals 180, so $0.1S = 180$. 7. Solve for S: $$S = \frac{180}{0.1} = 1800$$. Answer: Siew Ling's salary was 1800.