Final answer:
The expression -3 * 5/4 is equivalent to -15/4.
Step-by-step explanation:
When multiplying fractions or rational numbers, we multiply the numerators and denominators separately. In this case, we have (-3) * (5/4), which can be written as (-3/1) * (5/4). Multiplying the numerators and denominators gives us a final answer of -15/4. Therefore, the expression -3 * 5/4 is equivalent to -15/4