The inequality is .

Subtract 7 from each side.

Multiply each side by .

The solution set is .

Check:

To check, substitute three different values for z into the original inequality: negative 48, a number less than negative 48, and greater than negative 48.

Let three values are substitute in the original inequality, .

If then      (This is false)

If then      (This is true)

If then             (This is true) .

The solution set is .