Part of $9000 was invested at 10% interest and the rest at 12%. If the annual income from these investments was $1020 how much was invested at each rate?

Question

I must use 2 variables and 2 equations. 

Im lost on the setup.

Answer 1

Let x = the amount invested at 10%.  Since a total of $9000 was invested, the amount invested at 12% is $9000-x.

 

(0.1)x + (0.12)(9000-x) = 1020

 

Where 0.1 is the decimal equivalent of 10% and 0.12 is the decimal equivalent of 12%.

 

(0.1)x + 1080 - (0.12x) = 1020

 

Solve for x.