For the second one, we have
11.5x - 2.3y ≤ 20
11.5 (-10) - 2.3(10) ≤ 20 ⇒ -138 ≤ 20 which is true
11.5 (10) - 2.3(-10) ≤ 20 ⇒ 138 ≤ 20 which is false
11.5 (0) - 2.3(5) ≤ 20 ⇒ -11.5 ≤ 20 which is true
11.5 (1) - 2.3(0) ≤ 20 ⇒ 11.5 ≤ 20 which is true
So....a, c and d are correct
