4/21 + 1/6 x 2/7 = ………

4/21 + (1/6 x 2/7)
= 4/21 + (1/3 x 1/7)
= 4/21 + 1/21
= 5/21

4/21 + 1/6 x 2/7 = 4/21 + 2/42
= 8/42 + 2/42
= 10/42
= 5/21