We cannot go any further just yet. What if a-c=0? What if a-c is a negative number? There are actually four cases we need to consider for this inequality.
First case: &a = c and d > b
Second case: &a = c and d < b
Third case: &a > c
Fourth case: &a < c
Let's look at these cases one at a time.
First Case
In the first case, we should consider when a=c and d>b. When a=c we have a-c=0.
In the third case, we should consider when a>c. When a>c, we must have that a-c will always be a positive number in which case we can simply divide and keep the inequality symbol as it is.
