SOLUTION: Clara earned 780 dollars during Spring break. She invested part of her money at 3 \% and the rest at 4 \%. If she received a total of 27.5 dollars in interest at the end of the y

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Question 901119: Clara earned 780 dollars during Spring break. She invested part of her money at 3 \% and the rest at 4 \%. If she received a total of 27.5 dollars in interest at the end of the year, how much was invested at 4 \%?
Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
x+y=780,
0.03*x+0.04*y=27.5
x=780-y
0.03*(780-y)+0.04*y=27.5
23.4-0.03y+0.04*y=27.5
0.01*y=4.1
y=410.0 at 4%
x=780-y
x=370.0 at 3%
check
0.03*370.0+0.04*410.0=27.5
11.1+16.4=27.5
27.5=27.5
ok