Answer:
![5b=2r](https://img.qammunity.org/2021/formulas/mathematics/middle-school/kxs4hl9jswsjhgcqrtgtrhmrbweom9hyu2.png)
Explanation:
Given: For every 45 pieces of blue yarn Sofia uses, she uses 18 pieces of red yarn
To find: equation that can be used to represent the proportional relationship between the amount of blue yarn, b, and red yard, r
Solution:
As for every 45 pieces of blue yarn Sofia uses, she uses 18 pieces of red yarn,
number of pieces of blue yarn / number of pieces of red yarn =
![(18)/(45)=(2)/(5)](https://img.qammunity.org/2021/formulas/mathematics/middle-school/j2o6e0a92flq2wpmricqsu0mb80pne2fns.png)
![(b)/(r)=(2)/(5)\\ 5b=2r](https://img.qammunity.org/2021/formulas/mathematics/middle-school/75402v0ruf4j8nwizq2kinuoulwk6rukn7.png)
Therefore,
equation that can be used to represent the proportional relationship between the amount of blue yarn, b, and red yard, r is
![5b=2r](https://img.qammunity.org/2021/formulas/mathematics/middle-school/kxs4hl9jswsjhgcqrtgtrhmrbweom9hyu2.png)