Kristen invested a total of $12,000, part at 4% and part at 6%. How much did she invest in the LOWER interest account if the total interest earned in one year was $640?

set each factor equal to 0

4x-3 = 0

2x-1 = 0

solve for x.

4x-3=0

4x=3

x= 3/4

solve for x. 

2x-1= 0

2x= 1

x= 1/2

your answer should be 1/2 is less than or equal to x and 3/4 is greater than or equal to x

you bought 31 v bucks

step-by-step explanation:

25+6=31