Question 413009
let {{{a}}} = kilograms of Brazilian coffee needed
let {{{b}}} = kilograms of Turkish coffee needed
given:
(1) {{{ (11a + 13b)/(a + b) = 12}}} dollars/kg
(2) {{{a + b = 480}}} kg
------------------------
(1) {{{ (11a + 13b)/(a + b) = 12}}}
(1) {{{ 11a + 13b = 12*(a + b) }}}
(1) {{{ 11a + 13b = 12a + 12b}}}
(1) {{{a = b}}}
and, since,
{{{a + b = 480}}}
{{{a = 240}}} kg
{{{b = 240}}} kg
240 kg of each should be used
check answer:
(1) {{{ (11*240 + 13*240)/480 = 12}}}
(1) {{{2640 + 3120 = 12*480}}}
(1) {{{5760 = 5760}}}
OK