Question

The length and breadth of the model are 40 cm and 20 cm

Answer 1

$\orange{hey\:mate}$⤵
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⏬⏬⏬⏬⏬⏬⏬⏬⏬⏬⏬⏬⏬⏬⏬⏬⏬⏬⏬⏬⏬⏬⏬⏬⏬

ᴩᴇʀɪᴍᴇᴛᴇʀ ᴏꜰ ᴛʜᴀᴛ ᴍᴏᴅᴇʟ=2(ʟ+ʙ)
=2(40+20)ᴄᴍ
=2×60
=120ᴄᴍ
ᴀʀᴇᴀ ᴏꜰ ᴛʜᴀᴛ ᴍᴏᴅᴇʟ=ʟ×ʙ
=40ᴄᴍ×20ᴄᴍ
=800ᴄᴍ²
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$\orange{hope\:it\:helps}$