Interval notation is 1∠ x≤ 2
Explanation
-21≤-6x-9∠ -15
-21≤-6x-9
Grouping the terms, yield
-21+9≤-6x
-12≤-6x
⇒ -6x≥-12
x ≤ 2
Also, -6x-9∠ -15
-6x∠ -15+9
-6x∠ -6
⇒ x is greater 1
Then by combinig the inequalities x is greater than 1 and x ≤ 2, this yields
1∠ x≤ 2
