Question Video: Writing and Solving Linear Equations Mathematics • 6th Grade

The total cost of a skateboard and kneepads is $247. If the skateboard costs $235, write an equation to find the cost of the kneepads, 𝑘. Then, solve the equation.


Video Transcript

The total cost of a skateboard and knee pads is 247 dollars. If the skateboard costs 235 dollars, write an equation to find the cost of the kneepads, 𝑘. Then solve the equation.

The problem is asking us to do two things, write an equation and then solve the equation that we write. We’re given three different pieces of information. The total cost is 247 dollars. The skateboard costs 235 dollars. And the missing cost, the cost that we don’t know, is 𝑘, and that’s the cost of the kneepads. We know that the total cost equals the skateboard price plus the kneepads price. Let’s substitute these two pieces with the information that we already know. Total cost is 247. Skateboard costs 235. What should we put here for the knee pads price? Because we don’t know the knee pads price, we need to substitute a variable here. In our case, that’s where the 𝑘 goes. Our equation becomes 247 equals 235 plus 𝑘.

Step one of the problem is complete. This is an equation we can use to solve step two. And this part can be done mentally. What added to 235 would equal 247? Well, if you add ten, you get from 235 to 245 add two more to that and now you’re at 247. Put both of those numbers you added together, 10 and two, and you realise that 𝑘 must be equal to 12. 𝑘 is equal to twelve. And that means the kneepads cost 12 dollars. Our final answer here is 𝑘 equals 12 dollars.

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