<PRE><B>Question 520163</B>
Let {{{a}}} = pounds of peanuts
Let {{{b}}} = pounds of fancy nuts
given:
(1) {{{ a + b = 13 }}}
(2) {{{ 2.5a + 6.5b = 64.5 }}}
----------------------
(2) {{{ 25a + 65b = 645 }}}
(2) {{{ 5a + 13b = 129 }}}
Multiply both sides of (1) by {{{5}}}
and subtract (1) from (2)
(2) {{{ 5a + 13b = 129 }}}
(1) {{{ -5a - 5b = -65 }}}
{{{ 8b = 64 }}}
{{{ b = 8 }}}
and, since
(1) {{{ a + b = 13 }}}
(1) {{{ a = 5 }}}
5 pounds of peanuts are needed
8 pounds of fancy nuts are needed</PRE>