Hi,

1/4x+1/3y= 5    || |multiplying thru by 3 to  eliminate the y variable 

 x - y= 6             





   x = 

    x = 12    and  y = 6

and

 

 

 

Answer by DrBeeee(684)   (Show Source): You can put this solution on YOUR website!
 Given:

(1) x/4 + y/3 = 5

(2) x   - y   = 6

Solve by addition.

Multiply both sides of (1) by 3

3*(x/4 + y/3) = 3*(5)

3*(x/4) + 3*(y/3) = 15 yields

(3) 3/4*x + y = 15

Now add (2) + (3)

(1+3/4)*x + (1-1)*y = 6 + 15 which reduces to

7/4*x   + 0*y = 21  or

(4) 7/4*x = 21

    x = (4/7)*21

    x = 84/7

    x = 12

Then using (2)

    y = x - 6

    y = 6

Are these values correct? Let's see.

Put x = 12 and y = 6 into (1)

Is (12/4 + 6/3 = 5)?

Is (3 + 2 = 5)?

Is (5 = 5)? Yes

The answer is x = 12 and y = 6

PS We don't need to check our answer in equation (2) because we used it to derive the value of y.



 

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