`8 /` `A= 3/10 + 3/40 + 3/88 + ... + 3/340`
`A= 3/2.5 + 3/5.8 + 3/8.11 + ..... + 3/17.20`
`A= 1/2 - 1/5 + 1/5 - 1/8 + 1/8 - 1/11 + ..... + 1/17 + 1/20`
`A= ( -1/5 + 1/5 ) + ( -1/8 + 1/8 ) + ..... + ( -1/17 + 1/17) + 1/2 - 1/20`
`A= 1/2 - 1/20`
`A= 10/20 - 1/20`
`A= 9/20`
`9 /` `A=3^2/10 + 3^2/40 + 3^2/88 + ... + 3^2/340`
`A=3 . ( 3/2.5 + 3/5.8 + 3/8.11 + ..... + 3/17.20 )`
`A=3 . ( 1/2 - 1/5 + 1/5 - 1/8 + 1/8 - 1/11 + ..... + 1/17 + 1/20 )`
`A=3 . [( -1/5 + 1/5 ) + ( -1/8 + 1/8 ) + ..... + ( -1/17 + 1/17) + 1/2 - 1/20 ]`
`A=3 . ( 1/2 - 1/20 )`
`A=3 . ( 10/20 - 1/20 )`
`A=3 . 9/20`
`A=27/20`