Question 1005983
Let {{{ a }}} = pounds of nuts needed
Let {{{ b }}} = pounds of raisins needed
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(1) {{{ a + b = 90 }}}
(2) {{{ ( 12a + 6b ) / 90 = 8 }}}
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(2) {{{ 12a + 6b = 720 }}}
(2) {{{ 2a + b = 120 }}}
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Subtract (1) from (2)
(2) {{{ 2a + b = 120 }}}
(1) {{{ -a - b = -90 }}}
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{{{ a = 30 }}}
and
(1) {{{ a + b = 90 }}}
(1) {{{ b = 60 }}}
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30 pounds of nuts are needed
60 pounds of raisins are needed
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check:
(2) {{{ ( 12a + 6b ) / 90 = 8 }}}
(2) {{{ ( 12*30 + 6*60 ) / 90 = 8 }}}
(2) {{{ ( 360 + 360 ) / 90 = 8 }}}
(2) {{{ 720 = 8*90 }}}
(2) {{{ 720 = 720 }}}
OK