4/7+1/5-3/7+5/13=4/7-3/7+1/5+5/13=1/7+1/5+5/13=12/35+5/13=231/455
4/7+1/5-3/7+4/5=(4/7-3/7)+(1/5+4/5)=1/7+1=8/7
5.2-11÷7-1/7×2=26/5-11/7-2/7=26/5-(11/7+2/7)=26/5-13/7=117/35
3/4×4÷4×3/4=(3/4×4)÷(4×3/4)=3÷3=1
1/2+1/4+1/8+1/16+1/32=16/32+8/32+4/32+2/32+1/32=31/32