Question 96963
4 1/5 x 10/21 x 9/20
= 21/5 * 10/21 * 9/20

21's cancel
5 reduces with 10

= 1/1 * 2/1 * 9/20

2 reduces with 20 

= 1 * 1* 9/10

= 9/10

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Cheers,
Stan H.