Question

Mary invested one amount at 9% simple interest, and a second amount at 6% interest, earning $18.12 in one year. If she had switched the amounts, she would have earned $17.88. What were the two amounts?

Answer 1

Let x is the first amount, y is the second:
then 9x + 6y = 18.12

Can you do the second one?

Answer 2

would it be x + y = 17.88

Answer 3

SWITCH the amounts x, y: 9x + 6y

Answer 4

6x + 9y = 17.88

Answer 5

do you add the two together
or just solve for the two equations

Answer 6

I am a little lost would the first answer for the first equation be x = 2.013333

Answer 7

not sure what you are saying. can you explain one of the equations

Answer 8

9x + 6y = 18.12 (1)
-> 6y = 18.12 - 9x
Do you understand this part?

Answer 9

yes does that apply to the other equation also

Answer 10

ok give me a min to try to figure it out please

Answer 11

6y = 18.12 - 9x
divide all by 6
y=3.02 - 9x/6
this is what i am getting and i dont think it is right

Answer 12

6x + 9y = 17.88
6x + 9(3.02 - 9x/6) = 17.88
6x + 27.18 - 81x/54 = 17.88
27.18 - 75x/54 = 17.88
-75x/54 = -9.3
-75x = -502.2
x = 6.696

Answer 13

do you not undersand what i am saying
or is it the wrong way

Answer 14

ok ty

Answer 15

6x + 9(3.02 - 9x/6) = 17.88
6x + 27.18 - 13.5x = 17.88
Question?

Answer 16

oh i see how you did that

Answer 17

9x/ 6 = 1.5x

Answer 18

6x + 27.18 -13.5x = 17.88
7.5x + 27.18 = 17.88
7.5x = 45.06
x=6.008

Answer 19

6x + 27.18 -13.5x = 17.88
-> - 7.5x = 17.88 - 27.18

Answer 20

-7.5x = 17.88 - 27.18
-7.5 =-9.3

Answer 21

x= 1.32

Answer 22

x = 1.32

Answer 23

x = 1.24
Do you use calculator?

Answer 24

yes sorry must hit wrong number

Answer 25

i am going to try

Answer 26

9x + 6y = 18.12 this equation right

Answer 27

9x + 6y = 18.12
9(1.24) + 6y = 18.12
11.16 + 6y = 18.12
6y = 6.96
y = 1.16

Answer 28

ok

Answer 29

no ty for all your help and being patient with me

Answer 30

i am still trying to learn the elimination method

Answer 31

yes i do can i give you a problem

Answer 32

9x + 6y = 18.12,
6x + 9y = 17.88

Answer 33

ok then what

Answer 34

ause i get confused

Answer 35

not sure what you mean. like this
6(9x + 6y = 18.12)
54x + 36y = 108.72

Answer 36

ok then what

Answer 37

6x + 9y = 17.88
9(6x + 9y = 17.88)
54x + 81y = 160.92

Answer 38

no

Answer 39

yes

Answer 40

ok

Answer 41

45y = 52.20
y = 1.16

Answer 42

So now, it's getting so easy!
I've guided you through both methods. Next time it's up to you to use which one :)

Answer 43

ty again

Answer 44

Don't forget to click on the blue "Best Response" button if you're happy with the guidance ;)