<PRE><B>Question 732008</B>
x = number of pounds of $5/pound tea in the mixture
y = number of pounds of $7/pound tea in the mixture
------------
(1) {{{ x + y = 50 }}}
(2) {{{ 5x + 7y = 314 }}}
--------------------
Multiply both sides of (1) by {{{ 5 }}}
and subtract (1) from (2)
(2) {{{ 5x + 7y = 314 }}}
(1) {{{ -5x - 5y = -250 }}}
{{{ 2y = 64 }}}
{{{ y = 32 }}}
and, since
(1) {{{ x + y = 50 }}}
(1) {{{ x = 18 }}}
18 pounds of $5/pound tea are needed
32 pounds of $7/pound tea are needed

</PRE>