$ T = a x + b $ ------------------------------- If $ a \lt 0 $: $ T \lt 0 $ for $ x \gt \frac {-b} {a} $ $ T \gt 0 $ for $ x \lt \frac {-b} {a} $ ------------------------------- If $ a \gt 0 $ :: $ T \gt 0 $ for $ x \gt \frac {-b} {a} $ $ T \lt 0 $ for $ x \lt \frac {-b} {a} $ ------------------------------- If $ a = 0 $ :: $ T $ has the sign of $ b $ -------------------------------

Got it !

$T \lt 0$      When ??

$T = -3x + 7$
$T = x - 3$
$T = 9x -6$

Answer

Sign of $T = -2x+12$ for $x=6$ $T = 0$
$T = x-5\gt 0$ for $x\gt ?$
$-3x \gt 3$ for $x ?$
$0x -1 \gt 3$ for $x ?$
$-4 \leq 0x$ for $x ?$