Question 212894
Let {{{a}}} = amount invested in 6% account
Let {{{b}}} = amount invested in 7% account
given:
(1) {{{a + b = 1200}}}
(2) {{{.06a + .07b = 79}}}
Multiply both sides of (2) by {{{100}}}
(1) {{{a + b = 1200}}}
(2) {{{6a + 7b = 7900}}}
Multiply both sides of (1) by {{{6}}} and
subtract (1) from (2)
(2) {{{6a + 7b = 7900}}}
(1) {{{-6a - 6b = -7200}}}
{{{b = 700}}}
And, since {{{a + b = 1200}}},
{{{a = 1200 - 700}}}
{{{a = 500}}}
$500 should be invested @ 6%
$700 should be invested @ 7%