a-maths!!!!
回答 (1)
2007-09-26 6:58 am
✔ 最佳答案
Let the number of days he worked be x.His original daily wage: $1800 / x
1800 = ( 1800/ x – 20 )( x + 1 )
1800 + 1800 / x – 20x – 20 = 1800
1800 – 20x2 – 20x = 0
x2 + x – 90 = 0
( x – 9 )( x + 10 ) = 0
x = 9 or – 10 ( rejected )
He worked for 9 days.
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