`a) B = ( 1 - 1/2 ) . ( 1 - 1/3 ) .... ( 1 - 1/( n + 1 ) )`
`B = 1/2 . 2/3 .... n/( n + 1 )`
`B = ( 1 . 2 .... n )/( 2 . 3 . 4 .... ( n + 1 ) )`
`B = 1/( n + 1 )`
`b) C = - 66 . ( 1/2 - 1/3 + 1/11 ) + 124 . ( - 37 ) + 63 . ( - 124 )`
`C = - 66 . ( 33/66 - 22/66 + 6/66 ) + 124 . ( - 47 ) + ( - 63 ) . 124`
`C = - 66 . 17/66 + 124 . [ ( - 47 ) + ( - 63 ) ]`
`C = - 17 + 124 . ( - 100 )`
`C = - 17 + ( - 124 )`
`C = - 141`
`c) D = 7/4 . ( 33/12 + 3333/2020 + 33333333/48484848 )`
`D = 7/4 . ( 11/4 + 33/20 + 11/16 )`
`D = 7/4 . ( 220/80 + 132/60 + 55/80 )`
`D = 7/4 . 407/80`
`D = 2849/320`
