x+1/35 + x+3/33 = x+5 /31 + x+7/29
<=>(x+1/35)+1 + (x+3/33)+1 = (x+5 /31)+1 + (x+7/29)+1
<=>(x+36/35)+(x+36/33)=(x+36/31)+(x+36/29)
<=>(x+36/35)+(x+36/33)-(x+36/31)-(x+36/29)=0
<=>(x+36)(1/35+1/33+1/31+1/29)=0
<=>x+36=0 ( vì 1/35+1/33+1/31+1/29$\neq$0)
<=>x=-36