`A=2021-(364/210+334/240+302/272+268/306+232/342+194/380)`
`A=2021-364(1/210+1/240+1/272+1/306+1/342+1/380)`
`A=2021-364(1/14.15+1/15.16+1/16.17+1/17.18+1/18.19+1/19.20)`
`A=2021-364(1/14-1/15+1/15-1/16+1/16-1/17+1/17-1/18+1/18-1/19+1/19-1/20)`
`A=2021-364(1/14-1/20)`
`A=2021-364(10/140-7/140)`
`A=2021-364. 3/140`
`A=2021-39/5`
`A=2021-7,8`
`A=2013,2`