Question Video: Evaluating Linear Equations Mathematics • 7th Grade

Given that 𝑦 βˆ’ 3π‘₯ = 7, calculate the value of π‘₯ when 𝑦 = 3.


Video Transcript

Given that 𝑦 minus three π‘₯ equals seven, calculate the value of π‘₯ when 𝑦 equals three.

We start with our equation 𝑦 minus three π‘₯ equals seven. And then, we plug in three for 𝑦. Our new equation says three minus three π‘₯ equals seven. We want to solve for π‘₯. And that means we’ll need to get π‘₯ by itself.

The next step will be subtracting three from both sides. On the left, three minus three equals zero. They cancel each other out. And on the right, seven minus three equals four. Again, we’re trying to isolate π‘₯.

Here, π‘₯ is being multiplied by negative three. To isolate this, we’ll divide by negative three on both sides of the equation.

Negative three divided by negative three equals one. They cancel out. π‘₯ equals four divided by negative three, which we can rewrite as negative four-thirds. When 𝑦 equals three, π‘₯ is equal to negative four-thirds.

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