Question 997352
Let {{{ a }}} = pounds of coffee A used
Let {{{ b }}} = pounds of coffee B used
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(1) {{{ 4.1a + 5.8b = 709.8 }}}
(2) {{{ b = 4a }}}
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(1) {{{ 41a + 58b = 7098 }}}
Substitute (2) into (1)
(1) {{{ 41a + 58*4a = 7098 }}}
(1) {{{ 41a + 232a = 7098 }}}
(1) {{{ 273a = 7098 }}}
(1) {{{ a = 26 }}}
26 pounds of coffee A were used
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check:
(2) {{{ b = 4a }}}
(2) {{{ b = 4*26 }}}
(2) {{{ b = 104 }}}
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(1) {{{ 41a + 58b = 7098 }}}
(1) {{{ 41*26 + 58*104 = 7098 }}}
(1) {{{ 1066 + 6032 = 7098 }}}
(1) {{{ 7098 = 7098 }}}
OK