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Solving a word problem using a system of linear equations

Solving a word problem using a system of linear equations-example-1

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In order to determine the weighs of the boxes, name x as the larger box and y as the smaller one.

Then, based on the given situation, you can write the following equations:

3x + 2y = 86

8x + 4y = 209

Solve the previous system of equations as follow:

Multiply the first equation by -2 and add the result to the second equation:

(3x + 2y = 86)(-2)

-6x - 4y = -172

8x + 4y = 209

-6x - 4y = -172

2x = 37

Solve the previous equation for x by dividing by 2 both sides:

x = 37/2

x = 18.5

Next, replace the previous value of x into any of the equations of the system, for instance, into the first equation, and solve for y:

3x + 2y = 86

3(18.5) + 2y = 86

55.5 + 2y = 86

2y = 86 - 55.5

2y = 30.5

y = 30.5/2

y = 15.25

Hence, the weighs of the boxes are:

larger box = 18.5 kg

smaller box = 15.25 kg

User Doolius
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