In the following, state whether A = B or not

In the following, state whether A = B or not :

(i) A = {a, b, c, d}; B = {d, c, b, a}
(ii) A = {4, 8, 12, 16}; B = {8, 4, 16, 18}
(iii) A = {2, 4, 6, 8, 10}; B = {x: x is positive even integer and x ≤ 10}
(iv) A = {x: x is a multiple of 10}; B = {10, 15, 20, 25, 30 ...}
Answer
(i) A = {a, b, c, d}; B = {d, c, b, a}
Both set has exactly same element a, b, c, and d.
Hence A = B

(ii) A = {4, 8, 12, 16}; B = {8, 4, 16, 18}
12 and 18 are two element which are not contain by both set A and B.
Hence, A ≠ B

(iii) A = {2, 4, 6, 8, 10}
Positive even integer less than 10 are 2, 4, 6, 8 and 10.
Hence, A = B

(iv) A = {x: x is a multiple of 10}
15 and 25 are not multiple of 10.
Hence,A ≠ B