This is probably wrong, but:
7i > 21u
And I don't think I can simplify that, can I? If I can: i > 3u
Here. FOIL it: (x - 4)(x + 7)
Not hard to do, really.
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Dammit Sirrus. Well, it wasn't correct. 3 * 7 = 21, not 28
And I stick with my problem