Question 1153667
Let {{{ A }}} = amount invested at 4%
{{{ 7000 - A }}} = amount invested at 6%
Use {{{ I = P*r*t }}}
----------------------------------------------
(1) {{{ I[1] = -A*.04*1 }}}
(2) {{{ I[2] = ( 7000 - A )*.06*1 }}}
(3) {{{ I[1] + I[2] = 308 }}}
-------------------------------------
Add (1) and (2)
{{{ I[1] + I[2] = -.04A + 420 - .06A }}}
{{{ 308 = 420 - .1A }}}
{{{ .1A = 420 - 308 }}}
{{{ .1A = 112 }}}
{{{ A = 1120 }}}
and
{{{ 7000 - A = 5880 }}}
-------------------------------
$1,120 = amount invested at 4%
$5,880 = amount invested at 6%
-------------------------------------
check:
(1) {{{ I[1] = -A*.04*1 }}}
(2) {{{ I[2] = ( 7000 - A )*.06*1 }}}
---------------------------------------
(1) {{{ I[1] = -1120*.04*1 }}}
(1) {{{ I[1] = -44.8 }}}
and
(2) {{{ I[2] = ( 7000 - A )*.06*1 }}}
(2) {{{ I[2] = 5880*.06*1 }}}
(2) {{{ I[2] = 352.8 }}}
and
(3) {{{ I[1] + I[2] = 308 }}}
(3) {{{ -44.8 + 352.8 = 308 }}}
(3) {{{ 308 = 308 }}}
OK