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Video: Writing and Solving One-Step Linear Equations in Word Problems

Bethani Gasparine

Samuel’s mother gave him coloring pencils for his birthday. He lost 43 of them at the park. If he has 40 left, write and solve an equation to find how many coloring pencils Samuel’s mother gave him.

01:18

Video Transcript

Samuel’s mother gave him coloring pencils for his birthday. He lost forty-three of them at the park. If he has forty left, write and solve an equation to find how many coloring pencils Samuel’s mother gave him.

Samuel would have the original amount that he received for his birthday, and then we would have to take away the number that he lost at the park, and then that would be equal to the number of pencils that he actually has left. So the original amount we don’t actually know. Let’s call that 𝑥.

He lost forty-three of them at the park, so let’s take away forty-three. Now that we’ve subtracted forty-three, it should be equal to the number of pencils that are left, and he has forty left. So 𝑥 minus forty-three equals forty.

Let’s go ahead and solve for 𝑥. To solve for 𝑥, we need to add forty-three to both sides of the equation. On the left, the forty-threes cancel. And on the right, forty plus forty-three is eighty-three.

This means Samuel’s mother gave him eighty-three coloring pencils for his birthday. Therefore, the equation to represent this would be 𝑥 minus forty-three equals forty, and 𝑥 is equal to eighty-three.