Question 1081282
{{{40A+25B=35*12}}}, to account of just the amount of pure fruit juice;
and
{{{A+B=12}}}, to account for volume of the blend.



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{{{8A+5B=84}}}
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{{{B=12-A}}}
Substitute for B.
{{{8A+5(12-A)=84}}}
{{{8A+60-5A=84}}}
{{{3A=24}}}
{{{highlight(A=8)}}}.  Now just evaluate B.