Question 339965
Let {{{a}}} = dollars invested at 9%
Let {{{b}}} = dollars invested at 8%
given:
(1) {{{a + b = 10000}}}
{{{.09a + .08b = 860}}}
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(2) {{{9a + 8b = 86000}}}
Multiply both sides of (1) by {{{8}}} and
subtract (1) from (2)
(2) {{{9a + 8b = 86000}}}
(1) {{{-8a - 8b = 80000}}}
{{{a = 6000}}}
And, from (1)
(1) {{{6000 + b = 10000}}}
{{{b = 4000}}}
$6000 was invested at 9% and
$4000 was invested at 8%
check:
{{{.09a + .08b = 860}}}
{{{.09*6000 + .08*4000 = 860}}}
{{{540 + 320 = 860}}}
{{{860 = 860}}}
OK