How do I solve this Mixture Problem?

Question

Tyler invested some money at 1.5% simple interest and some at 2.5% simple interest. The total amount of his investments was $28,000, and the interest he earned during the first year was $620. How much did he invest at each rate?

Answer 1

let x = the money invested at 1.5% interest then

$28,000 - x = the money invested at 2.5% interest so

 

(x)(.015) + ($28000-x)(.025) = $620

(.015 x) + ($700) - (.025 x) = $620

-.01 x = - $80

x = $8,000

 

so $8,000 was invested at 1.5% interest and  $20,000 was invested at 1.5% interest.

 

as a check.

$8,000 (.015) + $20,000(.025) = $620

$620 = $620