3) 3/8 * (-7/4) =

The problem asks to multiply a fraction by a negative fraction: \(\frac{3}{8} \times \left(-\frac{7}{4}\right)\).

1. Multiply the numerators: \(3 \times (-7) = -21\)
2. Multiply the denominators: \(8 \times 4 = 32\)
3. Combine the results: The resulting fraction is \(\frac{-21}{32}\).

Ответ: \(-\frac{21}{32}\)