Question 1025332
Let {{{ a }}} = pounds of white chocolate needed
Let {{{ b }}} = pounds of dark chocolate needed
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(1) {{{ a + b = 6 }}}
(2) {{{ ( 4a + 7b ) / 6 = 5 }}}
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(2) {{{ 4a + 7b = 30 }}}
Multiply both sides of (1) by {{{ 4 }}} and
subtract (1) from (2)
(2) {{{ 4a + 7b = 30 }}}
(1) {{{ -4a - 4b = -24 }}}
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{{{ 3b = 6 }}}
{{{ b = 2 }}}
and
(1) {{{ a + b = 6 }}}
(1) {{{ a = 4 }}}
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4 pounds of white chocolate are needed
2 pounds of dark chocolate are needed
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check:
(2) {{{ ( 4a + 7b ) / 6 = 5 }}}
(2) {{{ ( 4*4 + 7*2 ) / 6 = 5 }}}
(2) {{{ ( 16 + 14 ) / 6 = 5 }}}
(2) {{{ 30 = 30 }}}
OK