Answer:
20 roses cost $91.65
Explanation:
Given
1 dozen rose = $54.99
Required
Determine the cost of 20 roses
To calculate the proportion, we make use of:
![c = kx](https://img.qammunity.org/2021/formulas/mathematics/college/7pykifq0htnc93xxtj0utgkirvvhhqn7my.png)
Where
c = cost
k = constant of proportionality
x = number of roses
For a dozen rose
and
![x = 12](https://img.qammunity.org/2021/formulas/mathematics/high-school/585tdx4jizj0hgwm6l105rlaurx7sdkq3u.png)
So:
![c = kx](https://img.qammunity.org/2021/formulas/mathematics/college/7pykifq0htnc93xxtj0utgkirvvhhqn7my.png)
![54.99 = k * 12](https://img.qammunity.org/2021/formulas/mathematics/college/xpofdiqdxp2p0v3m8sybp36dbfq4x2vz4t.png)
![54.99 = 12k](https://img.qammunity.org/2021/formulas/mathematics/college/ecj2iuf03ve3xbr8gn36va27fiqe0o8im8.png)
![k = (54.99)/(12)](https://img.qammunity.org/2021/formulas/mathematics/college/xwpnes81obtvmejayjx5thzn8zicw1ta5j.png)
![k = 4.5825](https://img.qammunity.org/2021/formulas/mathematics/college/vrxl7mys1o532cgj869r0pkiwes1p48nq7.png)
For 20 roses
![c = kx](https://img.qammunity.org/2021/formulas/mathematics/college/7pykifq0htnc93xxtj0utgkirvvhhqn7my.png)
Where
![k = 4.5825](https://img.qammunity.org/2021/formulas/mathematics/college/vrxl7mys1o532cgj869r0pkiwes1p48nq7.png)
![x = 20](https://img.qammunity.org/2021/formulas/mathematics/middle-school/q1i7dn6ljir99re9fojnl8jwj6cyxusu19.png)
![c = 4.5825 * 20](https://img.qammunity.org/2021/formulas/mathematics/college/2f38o6zj998fl64nbqc9af8nm32xd3cgfn.png)
![c = 91.65](https://img.qammunity.org/2021/formulas/mathematics/college/gjfyc4409l76ef9mmn2slun3ffebmmqme1.png)