Question 373434
Let {{{a}}} = amount invested at 10%
Let {{{b}}} = amount invested at 8%
given:
(1) {{{a + b = 9500}}}
{{{.1a + .08b = 878}}}
(2) {{{10a + 8b = 87800}}}
Multiply both sides of (1) by {{{8}}}
and subtract (1) from (2)
(2) {{{10a + 8b = 87800}}}
(1) {{{-8a - 8b = -76000}}}
{{{2a = 11800}}}
{{{a = 5900}}}
and, since
(1) {{{5900 + b = 9500}}}
{{{b = 3600}}}
$5,900 was invested at 10% and $3,600 was invested at 8%
check answer:
{{{.1a + .08b = 878}}}
{{{.1*5900 + .08*3600 = 878}}}
{{{590 + 288 = 878}}}
{{{878 = 878}}}
OK