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Question Video: Solving One-Variable Equations Mathematics • 7th Grade

Solve 8𝑘 − 3 − 2𝑘 = 21.

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Video Transcript

Solve eight 𝑘 minus three minus two 𝑘 is equal to 21.

In order to solve this equation, we firstly need to group or collect the like terms. Eight 𝑘 minus two 𝑘 is equal to six 𝑘, so our equation becomes six 𝑘 minus three is equal to 21. From this point onwards, we can use our knowledge of inverse operations and the balancing method. We begin by adding three to both sides. This gives us six 𝑘 is equal to 24. Our final step is to divide both sides of the equation by six. Six 𝑘 divided by six is 𝑘, and 24 divided by six is four.

The solution to the equation eight 𝑘 minus three minus two 𝑘 equals 21 is 𝑘 equals four. We could check this answer by substituting four back in to the original equation.

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