Question 117100

Interest(I) equals Principal(P) times Rate(R) times Time(T) or I=PRT
Let x=amount invested at 15%
Then 10,000-x=amount invested at 7%
Interest at 15% =x*0.15*1 or 0.15x
Interest at 7%=(10,000-x)*0.07*1=0.07(10,000-x)

Now we are told that the total interest for the year was $1260 so our equation to solve is:

0.15x+0.07(10,000-x)=1260  get rid of parens

0.15x+700-0.07x=1260  subtract 700 from both sides
0.15x+700-700-0.07x=1260-700  collect like terms

0.08x=560  divide both sides by 0.08
x=$7000----amount invested at 15%
10,000-x=10,000-7000=$3000---------------amount invested at 7%

CK

7000*0.15+3000*0.07=1260
1050+210=1260
1260=1260

Hope this helps---ptaylor