Please explain how you got the answer.

Step-by-step explanation:

First, simplify the equation they give you

125x+200≥1200 > 125x≥1000>x≥8

So, x has to be greater than or equal to 8 which rules out b or d.

So the answers are narrowed down to a and c, the only difference is that the dot in A is filled in whereas the dot in c is not. In math, having a filled in circle means that value is included (≥ sign), so we will choose the answer a.