what is the value of y in the solution to the system of equations?

1/3x + 1/4y=1

2x - 3y = -30

A-8
B-3
C3
D8

Verified Answer :

Keywords

system of equations, linear equation, elimination method

we have

\(\frac{1}{3}x+ \frac{1}{4}y=1\)

Multiply by \(12\) both sides

\(4x+3y=12\) -----> linear equation A

\(2x-3y=-30\) -----> linear equation B

Applying the elimination method for solve the system of equations

Adds equation A and equation B

\(4x+3y=12 \\2x-3y=-30\\-------- \\4x+2x=12-30 \\6x=-18 \\x=-3\)

Find the value of y

\(4(-3)+3y=12\)

\(3y=12+12\)

\(y=8\)

therefore

the answer is the option D

\(8\)


Their is the system of linear equations \(\frac{1}{3} x+\frac{1}{4} y=1\) and \(2x-3y=-30\).

The solution of the given system of equation is 8. The correct answer is option D.

Given equations:

      \(\frac{1}{3} x+\frac{1}{4} y=1\)

      \(2x-3y=-30\)

Let

    \(\frac{1}{3} x+\frac{1}{4} y=1\)         ...........(i)

    \(2x-3y=-30\)     ..........(ii)

Look for terms that can be eliminated. The equations do not have any x or y terms with the same coefficients.

Multiply the equation (i) by 12 so they do have the same coefficient.

   \(12(\frac{1}{3} x+\frac{1}{4} y=1)\)

   \(4x+3y=12\)       .............(iii)

Adding equation (ii) and equation (iii)

     \(2x-3y=-30\\4x+3y=12\)

  ------------------------

    \(6x=-18\\x=\frac{-18}{6}\\x=-3\)

Substitute x = -3 into one of the original equations to find y.

   \(2(-3)-3y=-30\\-6-3y=-30\\-3y=-30+6\\y=\frac{-24}{-3} \\y=8\)

Therefore, the answer is the option D

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