`B=1/9+8/9*13/17+8/9*4/17`
`B=1/9+8/9(13/17+4/17)`
`B=1/9+8/9 .1`
`B=1/9+8/9`
`B=1`
`C=4/11*(-2)/9+4/11*(-8)/9+4/11*1/9`
`C=4/11((-2)/9+(-8)/9+1/9)`
`C=4/11.(-1)`
`C=(-4)/11`
`D=5/1.6+5/6.11+5/11.16+...+5/51.56`
`D=1-1/6+1/6-1/11+1/11-1/16+...+1/51-1/56`
`D=1-1/56`
`D=55/56`