How much did Mark invest in each​ CD?

Question

Mark deposited a total of

​$25,000

in two different CDs. One CD paid

4.5​%

annual​ interest, and the other paid

3.5​%

annual interest. At the end of one​ year, he had earned

​$1075

in interest from the two CDs. How much did Mark invest in each​ CD?

Answer 1

X+Y= 25

4.5X + 3.5Y = 107.5

X=25-Y

4.5(25-Y) + 3.5Y = 107.5

112.5 -Y = 107.5

Y = 112.5 - 107.5 = 5 = $5,000 at 3.5%

X = 25-5 = 20= $20,000 at 4.5%