Final answer:
The expression equivalent to (-3)x + (-3)(-12) is -3x + 36, as the multiplication of two negative numbers yields a positive product.
Step-by-step explanation:
The question asks which expression is equivalent to (-3)x + (-3)(-12). To solve this, we need to apply the rule that when two negative numbers multiply, the answer has a positive sign. Based on this, (-3)(-12) equals 36 because 3 times 12 equals 36 and since both numbers are negative, the product is positive. Now, the expression simplifies to:
-3x + 36
This means the equivalent expression is -3x + 36, which is option A.