You would divide negative 3 (-3) from both sides to keep the c by itself. When you divide a positive by a negative it becomes negative.
Dividing 15 by -3 would equal -5, so c = -5
1) would be opposite of a sum property
2) it would be D
Cars usually on the freeway drive at 60 miles per hour or 96.56064 kilometers per hour. Speed x distance = result of kilometers or miles. In this case it is 96.56064 times 12 equals 1158.72768 kilometers per 12 hours.