Question 1015670
.
T=amount at 10%; S=amount at 6%
.
T+S=$12000
T=$12000-S . Use this to substitute for T below.
.
0.10T+0.06S=$1070 . Substitute for T from above.
0.10($12000-S)+0.06S=$1070
$1200-0.10S+0.06S=$1070
-0.04S=-$130
S=$3250
ANSWER 1: She should invest $3250 at 6%.
.
T=$12000-S=$12000-$3250=$8750
ANSWER 2: She should invest $8750 at 10%.
.
CHECK:
0.10T+0.06S=$1070
0.10($8750)+0.06($3250)=$1070
$875+$195=$1070
$1070=$1070
.