Shirley invested a total of $12,000 in two certificates of deposit. One pays 6% interest, and the other pays 7% interest. Her total interest at the end of one year is $790. How much is invested in the CD that pays 6% interest?

Question

anonymous · Answer

put $x$ as the amount invested at 6% interest, then the rest $12000-x$ gets 7% for a total of 
$$.06x+.07(12,000-x)$$ interest 
since you know the total is 790 solve 
$$.06x+.07(12,000-x)=790$$ for $x$

anonymous · Answer

probably easier to multiply both sides by 100 and solve 
$$6x+7(12,000-x)=79,000$$