The correct answers are:
(1) 2/3 of 18 is

(2) 2/3 of 24 is

Step-by-step explanation:
(1) Simply translate "What is 2/3 of 18" mathematically as follows:

Where,
x represents "what" in the sentence
= represents "is."
* represents "of."
Now solve to get the answer:

Hence the correct answer is: 2/3 of 18 is 12.
(2) Simply translate "What is 2/3 of 24" mathematically as follows:

Where,
x represents "what" in the sentence
= represents "is."
* represents "of."
Now solve to get the answer:

Hence the correct answer is: 2/3 of 24 is 16.