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Let `R={x|x inN,x" is a multiple of 3 and x"le100}` `S={x|x in N, x" is a multiple of 5 and x "le100}` What is the number of elements in `(RxxS)nn(SxxR)`?A. 36B. 33C. 20D. 6

Answer» Correct Answer - A
Let R = `R={x:x in N, x" is a multiple of 3 and "xle100}`
and `S={x:x in N, x" is a multiple of 5 and "xle100}`
`thereforeR={3, 6, 9, 12, 15, ....,99}`
and `S = {5, 10, 15, …., 95, 100}`
Now, `(RxxS)nn(SxxR)=(RnnS)xx(SnnR)`
=(15, 30, 45, 60, 75, 90)`xx`(15, 30, 45, 60, 75, 90)
`therefore` Number of elements in `(RxxS)nn(SxxR)`
`=6xx6=36`


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