Let x be the length of the shorter piece of the wire.
Then, the longer piece of the wire will be 70-x cm.
According to the question,
2/5 of the longer piece is equal to the shorter piece.
Therefore,
2/5 (70-x) = x
⇒ 2/5 x 70 - 2/5 x = x
⇒ 2x = 70
⇒ x = 70/2 = 35
Therefore, the shorter piece would be 35 cm.

However, since the question asked for the length of the shorter piece in centimetres,
the answer is 35 cm = 35 x 10 = 350 cm = 20 cm.
Hence, the correct answer is Option D - 20 cm.

Explanation:
The question asked for the length of the shorter piece of wire in centimetres when it is cut into two pieces, so that one piece will be 2/5th of the other. In order to solve this question, we must first find the length of the shorter piece. To do this, we used the equation 2/5 (70-x) = x where x is the length of the shorter piece of the wire. Solving for x, we get x = 70/2 = 35. Since the question asked for the length of the shorter piece in centimetres, the answer is 35 cm = 35 x 10 = 350 cm = 20 cm. Therefore, the correct answer is Option D - 20 cm.

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