How do you solive this problem?

10.5z + 16 ≥ 12.5z + 12

You can solve linear inequalities exactly like equations, except if you multiply/divide both sides by a negative number, you change the direction of the sides. So first, add and subtract what is needed to combine like terms on either sides of the inequality:

-2z ≥ -4

Now divide both sides by -2, changing the direction of the sign:

z ≤ 2