Textbook example 1C.1

[Kayko Lee 1C]

In the textbook example 1C.1 I wasn't sure on how they got to the first step of the problem. Since I can't post any pictures I'm talking about the equation shown above the image with the green box in the problem; the first step in case anyone looks at the text book for this. Thank you so much for any help! ><

[Brianne Conway 1D]

If you go up to Figure 1C.4, there is a paragraph above that figure and then an equation above that paragraph. That is Equation 4, the equation they're talking about in step 1. Equation 4 is simply derived from Equation 3, which you'll find if you go up a little more; it's right above the green subtitle "What Does This Equation Tell You?". If you look at the two equations side by side, you can see they derived Equation 4 from Equation 3 pretty much just through basic algebra. And then for Example 1C.1, they just plugged in the values from the problem into that exact equation. Hope this helps!