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# Explain the Logic to find x and y from the following equations?

hello,
how to find x and y from these two,
5x+3y=10
3x+5y=20 ??  Reply With Quote

2. Giraffe
Join Date
Jun 2012
Posts
234

## Re: Explain the Logic to find x and y from the following equations?

The logic is simple.The basic logic is to first find the value of either x or y using the two given equation.This can be achieved by-
1.Multiply the entire 1st equation with 3.

2.Multiply the entire 2nd equation with 5.
The resultant equations become-
15x+9y=30
15x+25y=100

3.Now subtract equation 1st from 2nd,we get:
15x+25y=100
-15x-9y=-30
It becomes->16y=70
Thus,y=70/16=4.375

4.Now,put the value of y on 1st equationn to get x.
5x+3*4.375=10
=>x=10-13.125/5
=>x=0.625  Reply With Quote

3. raki!!!
Join Date
Aug 2012
Location
Posts
280

## Re: Explain the Logic to find x and y from the following equations?

let 5x+3y=10 be equation1
& 3x+5y=20 be equation2

multiply equation1 with 3 and equation2 with 5

substract the resultant equations and find value of y

the substitute value of y in any of the 2 equations and find value of x

thus we found x,y values  Reply With Quote

4. Anupama Niranjana
Join Date
Jul 2012
Posts
39

## Re: Explain the Logic to find x and y from the following equations?

Hi Dear,
The logic is very easy.
step 1- let the 5x+3y=10 be equation 1
& 3x+5y=20 be equation 2

step 2- Multiply equation 1 with 3 and equation 2 with 5,then the two equations will be:
15x+9y=30
15x+25y=100

step 3- Now equation 2 - equation 1,we get
y=4.375

step 4- Substitute the value of y in any of the two equation and you will get the value of x i.e.
x=0.625.  Reply With Quote

5. lakshmi dhana
Join Date
May 2012
Location
kk
Posts
1,299

## Re: Explain the Logic to find x and y from the following equations?

5x+3y=10
3x+5y=20

>>make the coefficient of one variable to be same

>>Cancel them by adding/subtracting two equations

>>Find out the value of one variable

>>Substitute it in any one of the equation and find out the other variable...

Ans:x=0.625,y=4.375  Reply With Quote

6. sriniwaas
Join Date
Oct 2012
Posts
69

## Re: Explain the Logic to find x and y from the following equations?

hi it is simple,
5x+3y=10.........(1)
3x+5y=20..........(2) let these two equations

multiply equation 1 with number 3 and
multiply equation 2 with number 5
then it will be 15x + 9y=30............(1)
15x+25y=100..........(2)
now subtract equation 2 with 1 you get 6y=70
now you can find the 'y' value as y=11.67
substitute the Y value in equation 1or2.
if equation ........(1)
5x+3(11.67)=10
5x+35=10
5x=10-35
5x=-25
x=-25/5
x= -5
you can check the answer by substituting the X,Y values in equation 1or2
the same procedure for equation..............(2)

all the best  Reply With Quote