SOLUTION: Hi, I'm trying to write an equation to solve this problem and running into difficulty: I have 300000 to invest. A safe investment earns 3.5% per year. A risky investment yields

Algebra ->  Finance -> SOLUTION: Hi, I'm trying to write an equation to solve this problem and running into difficulty: I have 300000 to invest. A safe investment earns 3.5% per year. A risky investment yields       Log On


   

Question 1043568: Hi, I'm trying to write an equation to solve this problem and running into difficulty:
I have 300000 to invest. A safe investment earns 3.5% per year. A risky investment yields 7% a year. How much is needed to be invested at each rate to earn $15,000 per year.
I'm certain it has something to do with the simple interest formula but I just can't make this work. I get that SI=prt, but I can't work out beyond that.
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
(How many years?) The wording implies just 1 year.

The description works like a mixture problem.

x amount for risky
y amount for safe
system%28x%2By=300000%2C0.07x%2B0.035y=15000%29

STEPS
7x%2B3.5y=1500000
-
y=300000-x
-
7x%2B3.5%28300000-x%29=1500000
7x%2B1050000-3.5x=1500000
3.5x%2B1050000=1500000
3.5x=450000
highlight%28system%28x=128571%2Cy=171429%29%29