Big Ideas Math Integrated I, 2016
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Big Ideas Math Integrated I, 2016 View details
1. Solving Systems of Linear Equations by Graphing
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Exercise 28 Page 222

Use the given information to build a system of equations.

Number of Large Candles: 16
Number of Small Candles: 12

Practice makes perfect

We are told that we sold total of 28 candles. If we let s be the number of small candles sold and l be the number of large candles sold, we can write an equation to represent the total number of candles. 28= s+ l We will rearrange this equation by isolating one of the variables l to use it later easily. l=- s +28We also know that a large candle costs $6 and a small candle costs $4. With that information we will express how much we collected in terms of s and l.

Verbal expression Algebraic expression
Price per large candle 6
Number of large candles sold l
Money collected from selling large candles 6 l
Price per small candle 4
Number of small candles sold s
Money collected from selling small candles 4 s
Total amount of money collected 6 l+ 4 s

Since we collected $ 144, let's build an equation to express the total amount of money with the number of the candles. 6 l+ 4 s=144 Now, we will rearrange this equation by isolating l because it will help us graph this equation.

6l+4s=144
6l=-4s+144
l=-4/6s+24
l=-2/3s+24
l=- 2/3s+24

Now that we have both equations in slope-intercept form, we can plot them and find the point of interception.

From the graph we can see that point (12,16) is the solution. However, we should check the point by substituting it into the equations. Let's start with the first one.

l? =- s+28
16? =- ( 12)+28
16 ? = -12+28
16=16 ✓

Now let's check the second one.

l? =- 2/3s+24
16? =-2/3( 12)+24
16 ? =-24/3+24
16? =-8+24
16=16 ✓

Since both equations hold true, point (12,16) is a solution. This means that you sold 12 small candles and 16 large candles.