Evaluate : 9.3% of 500 - 4.8% of 250 - 2.5% of 240

9.3% of 500 - 4.8% of 250 - 2.5% of 240 ⇒ of 500 - of 250 - of 240 ⇒ ⇒ 46.5 - 12 - 6 ⇒ 34.5 - 6 ⇒ 28.5 9.3% of 500 - 4.8% of 250 - 2.5% of 240 = 28.5

A number is decreased by 20%. If the resulting number is 800, the original number is :
640
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