Question 274150
Let {{{a}}} = amount invested at 6%
Let {{{b}}} = amount invested at 11%
given:
(1) {{{a + b = 10000}}}
{{{.06a + .11b = 700}}}
(2) {{{6a + 11b = 70000}}}
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Multiply both sides of (1) by {{{6}}}
and subtract (1) from (2)
(2) {{{6a + 11b = 70000}}}
(1) {{{-6a - 6b = -60000}}}
{{{5b = 10000}}}
{{{b = 2000}}}
And, from (1),
{{{a + 2000 = 10000}}}
{{{a = 8000}}}
$8000 should be invested at 6% and $2000 should be invested at 11%
check:
(2) {{{6a + 11b = 70000}}}
(2) {{{6*8000 + 11*2000 = 70000}}}
{{{48000 + 22000 = 70000}}}
{{{70000 = 70000}}}
OK