=>1/23-1/34+1/34-1/45+...+1/90-1/101+x=-1/101
=>x=1/23
`(11)/(23.34)+(11)/(34.45)+...+(11)/(90.101)+x=(-1)/(101)`
`=>(34)/(23.34)-(23)/(23.34)+(45)/(34.45)-(34)/(34.45)+...+(101)/(90.101)-(90)/(90.101)+x=(-1)/(101)`
`=>(1)/(23)-(1)/(34)+(1)/(34)-(1)/(45)+...+(1)/(90)-(1)/(101)+x=(-1)/(101)`
`=>(1)/(23)-(1)/(101)+x=(-1)/(101)`
`=>(1)/(23)+x=(-1)/(101)+(1)/(101)`
`=>x+(1)/(23)=0`
`=>x=-1/23`