## The problem

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why does the sign change from greater than or equal to to less than or equal to

## Answer provided by our tutors

If each side of an inequality is multiplied by the same negative number (in your case it is '-1'), then the sign will flip, or in your case from greater than or equal to less than or equal to.

This can be also explained another way: if we add 'a + 9' on both sides of the inequality we get

Or this is the same as