1. The problem asks to find $\frac{3}{5}$ of 400. 2. To find a fraction of a number, multiply the fraction by the number. 3. Calculate $\frac{3}{5} \times 400$. 4. Multiply the numerator by 400: $3 \times 400 = 1200$. 5. Divide by the denominator: $\frac{1200}{5} = 240$. 6. Therefore, $\frac{3}{5}$ of 400 is 240.