`A=7/4·((3333)/(1212)+(3333)/(2020)+(3333)/(3030)+(3333)/(4242)`
`A=7/4·[(3333)/(101)·(1/12+1/20+1/30+1/42)]`
`A=7/4·[(3333)/(101)·(1/(3·4)+1/(4·5)+1/(5·6)+1/(6·7)]`
`A=7/4·[(3333)/(101)·(1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7)]`
`A=7/4·[(3333)/(101)·(1/3-1/7)]`
`A=7/4·(3333)/(101)·4/21`
`A=(1111)/(101)`
`A=11`