Question 1103656
Let {{{ a }}} = pounds of type A needed
Let {{{ b }}} = pounds of type B needed
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(1) {{{ a + b = 144 }}}
(2) {{{ 4.15a + 5.7b = 734 }}}
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(2) {{{ 415a + 570b = 73400 }}}
Multiply both sides of (1) by {{{ 415 }}} and
and subtract (1) from (2)
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(2) {{{ 415a + 570b = 73400 }}}
(1) {{{ -415a - 415b = -59760 }}}
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{{{ 155b = 13640 }}}
{{{ b = 88 }}}
and
(1) {{{ a + b = 144 }}}
(1) {{{ a + 88 = 144 }}}
(1) {{{ a = 56 }}}
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she needs 88 pounds of type B coffee
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check:
(2) {{{ 4.15a + 5.7b = 734 }}}
(2) {{{ 4.15*56 + 5.7*88 = 734 }}}
(2) {{{ 232.4 + 501.6 = 734 }}}
(2) {{{ 734 = 734 }}}
OK