Question 104422
6 1/8={{{6+1/8}}}={{{6*1+1/8}}}={{{6*(8/8)+1/8}}}={{{48/8+1/8}}}={{{(48+1)/(8)}}}
_____={{{49/8}}}

5 3/4={{{5+3/4}}}={{{5*1+3/4}}}={{{5*(4/4)+3/4}}}={{{(20+3)/(4)}}}={{{23/4}}}


Thus,

{{{b+49/8=3/4}}}
{{{8(b+49/8)=8(3/4)}}}
{{{8b+49=6}}}
{{{8b+49-49=6-49}}}
{{{8b+0=-43}}}
{{{8b=-43}}}
{{{8b/8=-43/8}}}
{{{b=-43/8}}}


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