Question 974970
Let {{{ a }}} = number of $5 bills
Let {{{ b }}} = number of $10 bills
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(1) {{{ a + b = 76 }}}
(2) {{{ 5a + 10b = 580 }}}
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Multiply both sides of (1) by {{{ 5 }}}
and subtract (1) from (2)
(2) {{{ 5a + 10b = 580 }}}
(1) {{{ -5a - 5b = -380 }}}
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{{{ 5b = 200 }}}
{{{ b = 40 }}}
and
(1) {{{ a + 40 = 76 }}}
(1) {{{ a = 36 }}}
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She has 36 $5 bills and
40 $10 bills
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check:
(2) {{{ 5a + 10b = 580 }}}
(2) {{{ 5*36 + 10*40 = 580 }}}
(2) {{{ 180 + 400 = 580 }}}
(2) {{{ 580 = 580 }}}
OK