Question 374879
Let A be the amount of $2.50/lb coffee, B the amount of $5.00/lb coffee.
1.{{{A+B=100}}}
.
.
.
{{{250A+500B=390(100)}}}
2.{{{A+2B=156}}}
Subtract eq. 1 from eq. 2,
{{{A+2B-A-B=156-100}}}
{{{highlight(B=56)}}}lbs
Then from eq. 1,
{{{A+56=100}}}
{{{highlight(a=44)}}}lbs