Question 501884
Let {{{a}}} = amount invested @ 5%
Let {{{b}}} = amount invested @ 4%
given:
(1) {{{ a + b = 11000 }}}
(2) {{{ .05a + .04b = 520 }}}
--------------------
(2) {{{ 5a + 4b = 52000 }}}
Multiply both sides of (1) by {{{4}}}
and subtract (1) from (2)
(2) {{{ 5a + 4b = 52000 }}}
(1) {{{ -4a - 4b =- 44000 }}}
{{{ a = 8000 }}}
and, since
(1) {{{ a + b = 11000 }}}
(1) {{{ 8000 + b = 11000 }}}
(2) {{{ b = 3000 }}}
$8,000 was invested @ 5% and $3,000 was invested @ 4%
check answer:
(2) {{{ .05a + .04b = 520 }}}
(2) {{{ .05*8000 + .04*3000 = 520 }}}
(2) {{{ 400 + 120 = 520 }}}
(2) {{{ 520 = 520 }}}
OK