Question 891351
Let {{{ a }}} = kg of Kenyan coffee needed
Let {{{ b }}} = kg of Turkish coffee needed
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(1) {{{ a + b = 504 }}} kg
(2) {{{ ( 10a + 13b ) / 504 = 12 }}}
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(2) {{{ 10a + 13b = 12*504 }}}
(2) {{{ 10a + 13b = 6048 }}}
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Multiply both sides of (1) by {{{ 10 }}}
and subtract (1) from (2)
(2) {{{ 10a + 13b = 6048 }}}
(1) {{{ -10a - 10b = -5040 }}}
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{{{ 3b = 1008 }}}
{{{ b = 336 }}}
and, since
(1) {{{ a + b = 504 }}}
(1) {{{ a = 504 - 336 }}}
(1) {{{ a = 168 }}}
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168 kg of Kenyan coffee are needed
336 kg of Turkish coffee are needed
check:
(2) {{{ ( 10*168 + 13*336 ) / 504 = 12 }}}
(2) {{{ 1680 + 4368 = 12*504 }}}
(2) {{{ 6048 = 6048 }}}
OK