Solve the systems by elimination (how to do work/answers already included)?

0.08x+0.02y=0.06

If you see the the LCM of 0.08, 0.02 and 0.06 is 0.02. Divide both sides by 0.02 to get

4x + y = 3

we also get y = 3 - 4x

The other equation is also 4x+y=3. So essentially we have just one equation for 2 variables and hence cannot solve it. That's why we have solution as (x, (3-4x))

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1st Equation:

3x/2 - y/3= -18

To get rid of denominator find LCM, which is 6

(9x - 2y)/6 = -18

9x - 2y = -108...........Equation A

2nd Equation:

3x/4 - 2y/9=-9

LCM is 36

(27x - 8y)/36 = -9

27x - 8y = -324..................Equation B

Now we solve the Equation A and Equation B

Let's get rid of y for that multiply Equation A by 4 and then subtract Equation B from it

36x - 8y = -432

-(27x - 8y = -324)

9x = -108

x = -12

Plug it in Equation A to get y

9(-12) - 2y = -108

-108 - 2y = -108

2y = 0

y = 0

Solution set is (-12, 0)

0.08x+0.02y=0.06 , divide by 0.02 ---->

4x+y=3

and 4x+y=3 ---->y = -4x+3

---->Answer: (x,y) = (x,-4x +3)