<PRE><B>Question 396320</B>
Let {{{a}}} = kilos of Brazilian coffee to use
Let {{{b}}} = kilos of Turkish Coffee to use
given:
(1) {{{(10a + 13b)/564 = 11}}}
(2) {{{a + b = 564}}}
Multiply both sides of (1) by {{{564}}}
(1) {{{10a + 13b = 6204}}}
Multiply both sides of (2) by {{{10}}}, and
subtract from (1)
(1) {{{10a + 13b = 6204}}}
(2) {{{-10a - 10b = -5640}}}
{{{3b = 564}}}
{{{b = 188}}}
and, from (2),
{{{a + 188 = 564}}}
{{{a = 376}}}
376 kilos of Brazilian coffee are needed
188 kilos of Turkish Coffee are needed



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