Question 91683: Lane invested $22,000, part at 8% and the other part at 7%. If the total interest at the end of the year is $1,710, how much did she invest at 8%?
Answer by tutorcecilia(2152)   (Show Source):
You can put this solution on YOUR website! Lane invested $22,000, part at 8% and the other part at 7%. If the total interest at the end of the year is $1,710, how much did she invest at 8%?
x+y=22,000
.08x+.07y=1710
Solving the system of equations using the substitution method:
.
x+y=22,000
x=-y+22,000 [plug this back into the second equation and solve for (y)]
.
0.08x+.07y=1710
.08(-y+22,000)+.07y=1710 [simply
-.08y-1760+.07y=1710 [combine like-terms]
-0.1y=-50
y=-50/-.01
y=5,000 [plugging (y=5,000) back into one of the original equations and solve for the x-term]
.
x+y=22,000
x+5000=22,000
x=22,000-5,000
x=17,000
.
So $17,000 was invested at 8%
and
$5,000 was invested at 7%
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