Solve by using the multiplication principle. \( 4 x=60 \) Choose the correct definition of the multiplication principle. A. \( b=c \) is equivalent to \( b \cdot c=a \). B. \( a=b \) is equivalent to \( b \cdot a=c \). C. \( b=c \) is equivalent to \( a \cdot c=b \cdot c \). D. \( a=b \) is equivalent to \( a \cdot c=b \cdot c \).

The multiplication principle (or multiplication property of equality) states that if a = b, then for any number c, a·c = b·c. This is exactly what option D states. Now, using this principle to solve 4x = 60: 1. Start with the equation: 4x = 60. 2. To isolate x, divide both sides by 4 (which is multiplying both sides by 1/4, an example of the multiplication principle). Thus,   x = 60/4. 3. Simplify: x = 15. So, x = 15 and the correct definition of the multiplication principle is option D: a = b is equivalent to a·c = b·c.