Question 149097
{{{a}}} = amount invested at 9%
{{{b}}} = amount invested at 8%
{{{a + b = 9000}}} and,
{{{a = 9000 - b}}}
{{{.09a + .08b = 770}}}
{{{.09*(9000 - b) + .08b = 770}}}
{{{810 - .09b + .08b = 770}}}
{{{-.01b = -40}}}
{{{b = 4000}}}
$4,000 was invested at 8%
check answer:
{{{a + b = 9000}}}
{{{a + 4000 = 9000}}}
{{{a = 5000}}}
{{{.09a + .08b = 770}}}
{{{.09*5000 + .08*4000 = 770}}}
{{{450 + 320 = 770}}}
{{{770 = 770}}}
OK