Answer:
D : t ≤ 1
Step-by-step explanation:
3t - 12 ≤ - 9
3t - 12 + 12 ≤ - 9 + 12
3t ≤ 3
3t/3 ≤ 3/3
t ≤ 1
For (≤ or <) Arrow points to the negative side
if the symbol is (≥ or ≤) then you fill in the dot
if the symbol is (> or <) then you do not fill in the dot
