`1)`

`B=81[(12-12/7-12/289-12/85)/(4-4/7-4/289-4/85):(5+5/13 + 5/169 + 5/91)/(6+6/13+6/169+6/91)].10/3^4`

`B=81*[(12(1-1/7 - 1/289 -1/85))/(4(1-1/7 - 1/289 -1/85)):(5(1+1/13+1/169+1/91))/(6(1+1/13+1/169+1/91))].10/3^4`

`B=81*10/3^4.[12/4:5/6]`

`B=3^4*10/3^4[3*6/5]`

`B=10*18/5`

`B=2*18`

`B=36`

`2)`

`A=1/31[31/5(9-1/2)-17/2(4+1/5)]+(1/2+1/6+1/12+...+1/930)`

`A=1/31*[31/5 * 17/2 - 17/2 * 21/5] + (1/1.2+1/2.3+1/3.4+...+1/30.31)`

`A=1/31*17/2*(31/5-21/5)+(1/1-1/2+1/2-1/3+1/3-1/4+...+1/30-1/31)`

`A=1/31*17/2*2+(1-1/31)`

`A=1/31*17+1-1/31`

`A=1/31*(17-1)+1`

`A=1/31*16+1`

`A=16/31+1`

`A=47/31`