Question 527745
He ends up with
{{{ .4*16 = 6.4 }}} ounces of pecans
Let {{{ a }}} = ounces of 25% mix needed
Let {{{ b }}} = ounces of 100% mix needed
given:
(1) {{{ a + b = 16 }}}
(2) {{{ .25a + b = 6.4 }}}
Multiply both sides of (2) by 
{{{ 100 }}}. Then multiply both 
sides of (1) by {{{25}}} and subtract
(1) from (2)
(2) {{{ 25a + 100b = 640 }}}
(1) {{{ -25a - 25b = -400 }}}
{{{ 75b = 240 }}}
{{{ b = 3.2 }}}
and, since
(1) {{{ a + b = 16 }}}
(1) {{{ a = 12.8 }}}
12.8 ounces of 25% mix are needed
3.2 ounces of 100% mix are needed