Problema Solution
Walt made an extra $10,000 last year from a part-time job. He invested part of the money at 10% and the rest at 9%. He made a total of $970 in interest. How much did he invest at each rate?
Answer provided by our tutors
let investment in 10% = $x
investment in 9% = $(10000-x)
interest earned = 10x/100 + 9(10000-x)/100
=> 10x + 90000 - 9x = 97000
=> x = 7000
investment in 10% = $7000
investment in 9% = $3000