Question 865301
Let {{{ a }}} = the amount she invested in 
the 1st fund
Let {{{ b }}} = the amount she invested in
the 2nd fund
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(1) {{{ a + b = 2500 }}}
(2) {{{ .2a + .08b = 320 }}}
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(2) {{{ 20a + 8b = 32000 }}}
(2) {{{ 5a + 2b = 8000 }}}
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Multiply both sides of (1) by {{{ 2 }}}
and subtract (1) from (2)
(2) {{{ 5a + 2b = 8000 }}}
(1) {{{ -2a - 2b = -5000 }}}
{{{ 3a = 3000 }}}
{{{ a = 1000 }}}
and, since
(1) {{{ a + b = 2500 }}}
(1) {{{ b = 1500 }}}
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She invested $1,000 in the 1st fund and
$1,500 in the 2nd fund
check:
(2) {{{ .2a + .08b = 320 }}}
(2) {{{ .2*1000 + .08*1500 = 320 }}}
(2) {{{ 200 + 120 = 320 }}}
(2) {{{ 320 = 320 }}}
OK