Question 529205
Let {{{ a }}} = amount invested @ 8%
Let {{{ b }}} = amount invested @ 10%
given:
(1) {{{ a + b = 8000 }}}
(2) {{{ .08a + .1b = 700 }}}
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(2) {{{ 8a + 10b = 70000 }}}
(2) {{{ 4a + 5b = 35000 }}}
Multiply both sides of (1) by {{{4}}}
and subtract (1) from (2)
(2) {{{ 4a + 5b = 35000 }}}
(1) {{{ -4a - 4b = -32000 }}}
{{{ b = 3000 }}}
and, since
(1) {{{ a + b = 8000 }}}
(1) {{{ a = 8000 - 3000 }}}
(1) {{{ a = 5000 }}}
$5,000 is the amount invested @ 8%
$3,000 is the amount invested @ 10%
check answer:
(2) {{{ .08a + .1b = 700 }}}
(2) {{{ .08*5000 + .1*3000 = 700 }}}
(2) {{{ 400 + 300 = 700 }}}
(2) {{{ 700 = 700 }}}
OK