SOLUTION: calvin invested $7500 for one year, part at 12% annual interest and the rest at 10% annual interest. His total for the year was $890. How much money did he invested at 12%?

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Question 232133: calvin invested $7500 for one year, part at 12% annual interest and the rest at 10% annual interest. His total for the year was $890. How much money did he invested at 12%?
Answer by Earlsdon(6103) About Me  (Show Source):
You can put this solution on YOUR website!
Let x = the amount invested at 12% per annum, then ($7500-x) would be the amount invested at 10% per annum.
The interest, whose sum is $890, earned on these two amounts can be expressed algebraically as:
x%280.12%29%2B+%287500-x%29%280.1%29+=+890 Simplify and solve for x.
0.12x%2B750-0.1x+=+890 Combine like-terms on the left.
0.02x%2B750+=+890 Subtracr 750 from both sides.
0.02x+=+140 Divide both sides by 0.02
x+=+7000
The amount invested at 12% is $7,000.00