-3,5 • 1 3/7

Let's convert the mixed number \( 1 \frac{3}{7} \) into an improper fraction and then multiply.

1. Convert \( 1 \frac{3}{7} \) to an improper fraction: \[ 1 \frac{3}{7} = \frac{7 \times 1 + 3}{7} = \frac{7 + 3}{7} = \frac{10}{7} \]

2. Now multiply \(-3.5\) by \(\frac{10}{7}\): \[ -3.5 \times \frac{10}{7} \]

Express \(-3.5\) as a fraction: \[ -3.5 = -\frac{7}{2} \]

3. Multiply: \[ -\frac{7}{2} \times \frac{10}{7} = -\frac{7 \times 10}{2 \times 7} \]

4. Simplify numerator and denominator: \[ -\frac{70}{14} = -\frac{70 \div 14}{14 \div 14} = -\frac{5}{1} = -5 \]

Final answer: \(-5\)