x/1*2+x/2*3+x/3*4+x/4*5+x/5*6+x/6*7+x/7*8=7/8
x(1/1*2+1/2*3+1/3*4+1/4*5+1/5*6+1/6*7+1/7*8)=7/8
x(1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7+1/7-1/8)=7/8
x(1-1/8)=7/8
x(7/8)=7/8
x=1