Answer:

HEllo the answer is 8

Explanation:

Using the formula

P=2(l+w)

Solving for w

w=P

2﹣l=40

2﹣12=8cm

hope it helps

Explanation:

Perimeter of rectangle is 2×(length +breadth)

40cm. = 2× (12+breadth)

40cm/2 = 12+breadth

20cm = 12+breadth

20cm -12cm. = breadth

8cm. = breadth

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