A1+A2+...+A100=100
A1+(A1+D)+(A1+2D)+...+(A1+99D)=100
100A1+D(1+2+...+99)=100
A1+49,5D=1
A101+A102+...+A200=200
(A1+100D)+(A1+101D)+...+(A1+199D)=200
100A1+D(100+101+...+199)=200
A1+149,5D=2
A1+149,5D-(A1+49,5D)=2-1
100D=1
D=1/100
A1+A2+...+A100=100
A1+(A1+D)+(A1+2D)+...+(A1+99D)=100
100A1+D(1+2+...+99)=100
A1+49,5D=1
A101+A102+...+A200=200
(A1+100D)+(A1+101D)+...+(A1+199D)=200
100A1+D(100+101+...+199)=200
A1+149,5D=2
A1+149,5D-(A1+49,5D)=2-1
100D=1
D=1/100