A total of 10,000 dollar was invested in two certificates of deposit at simple annual interest rates of 6 percent and 8 percent, respectively. if the total interest on the two certificates was 720 dollar at the end of one year, what fractional part of the 10,000 dollar was invested at the higher rate?
A. 3/8
b. 2/5
C. 1/2
D. 3/5
E. 3/4
A. 3/8
b. 2/5
C. 1/2
D. 3/5
E. 3/4
