a-1>-2, a>-2+1, a>-1.
a-2≤0, a≤2.
On a number line which includes, say, the numbers between -2 and +3, mark -1 and +2. The given inequalities is represented by the line segment between the marks. It includes the point 2 (usually represented by a tiny filled circle) but excludes the point -1 (usually represented by a tiny unfilled circle).