Question 1085480
Let {{{ a }}} = the previous balance
Let {{{ b }}} = the new charges
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(1) {{{ a + b + 39 = 420.9 }}}
(2) {{{ a = b - 172.4 }}}
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(1) {{{ a + b = 381.9 }}}
(2) {{{ -a + b = 172.4 }}}
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{{{ 2b = 554.3 }}}
{{{ b = 277.15 }}}
and
(2) {{{ a = b - 172.4 }}}
(2) {{{ a = 277.15 - 172.4 }}}
(2) {{{ a = 104.75 }}}
The previous balance is $104.75
The new charges are $277.15
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Check the answers
(1) {{{ a + b + 39 = 420.9 }}}
(1) {{{ 104.75 + 277.15 + 39 = 420.9 }}}
(1) {{{ 381.9 + 39 = 420.9 }}}
(1) {{{ 420.9 = 420.9 }}}
OK