1. State the problem: Write the ratio $2:5$ as a fraction, a decimal, and a percentage. 2. Interpret the ratio: The notation $2:5$ means 2 parts out of 5 parts in total. 3. Convert to a fraction: The ratio $2:5$ corresponds to the fraction $$\frac{2}{5}$$. 4. Simplify the fraction: The greatest common divisor of 2 and 5 is 1, so the fraction is already in simplest form, $$\frac{2}{5}$$. 5. Convert to a decimal: Divide the numerator by the denominator, $2\div5=0.4$. 6. Convert to a percentage: Multiply the decimal by 100, $0.4\times100=40\%$. 7. Final answer: The ratio $2:5$ equals the fraction $$\frac{2}{5}$$, the decimal $0.4$, and the percentage $40\%$.