Question 397195
Let {{{a}}} = amount invested @ 7%
Let {{{b}}} = amount invested @ 11%
given:
(1) {{{.07a + .11b = 1540}}}
(2) {{{a + b = 18000}}}
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Multiply both sides of (1) by {{{100}}}
(1) {{{7a + 11b = 154000}}}
Multiply both sides of (2) by {{{7}}}
and subtract (2) from (1)
(1) {{{7a + 11b = 154000}}}
(2) {{{-7a - 7b = -126000}}}
{{{4b = 28000}}}
{{{b = 7000}}}
and, from (2),
{{{a + 7000 = 18000}}}
{{{a = 11000}}}
$11,000 was invested @ 7%
$7,000 was invested @ 11%