Question 996833
Let {{{ a }}} = amount invested at 5.2%
Let {{{ b }}} = amount invested at 6%
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(1) {{{ a + b = 25000 }}}
(2) {{{ .052a + .06b = 1350 }}}
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(2) {{{ 52a + 60b = 1350000 }}}
(2) {{{ 13a + 15b = 337500 }}}
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Multiply both sides of (1) by {{{ 13 }}}
and subtract (1) from (2)
(2) {{{ 13a + 15b = 337500 }}}
(1) {{{ -13a - 13b = -325000 }}}
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{{{ 2b = 12500 }}}
{{{ b = 6250 }}}
and
(1) {{{ a + b = 25000 }}}
(1) {{{ a + 6250 = 25000 }}} 
(1) {{{ a = 18750 }}}
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$18,750 is invested at 5.2%
$6,250 is invested at 6%
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check:
(2) {{{ .052a + .06b = 1350 }}}
(2) {{{ .052*18750 + .06*6250 = 1350 }}}
(2) {{{ 975 + 375 = 1350 }}}
(2) {{{ 1350 = 1350 }}}
OK