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Answer:
(b) 25 cm²
Explanation:
The ratio of areas is the square of the ratio of linear dimensions.
ar(ΔABC)/ar(ΔDEF) = (AB/DE)² = (1/2)² = 1/4
Then ...
ar(ΔABC) = (1/4)(100 cm²) = 25 cm² . . . . . multiply by ar(ΔDEF)
The area of ΔABC is 25 cm².