Answer:
The required equation is 7=2+r and the value of r is 5 units.
Explanation:
In the given hanger, the left side of the hanger has 7 boxes in which each box is of one unit.
The sum of left sides is
![1+1+1+1+1+1+1=7](https://img.qammunity.org/2020/formulas/mathematics/middle-school/wviangdhmv7890robeo8n8bbivgxk5zgav.png)
The sum of left side is 7.
Right side of the hanger has 2 boxes in which each box is of one unit and pentagon of r units. So, the sum of right side is
![1+1+r=2+r](https://img.qammunity.org/2020/formulas/mathematics/middle-school/8ukg82pwjxtddp6ctao06hxv1fhdycm1zi.png)
It is given that the hanger represents a balanced equation. It means the left sides is equal to the right side. So, the required equation is
![7=2+r](https://img.qammunity.org/2020/formulas/mathematics/middle-school/ithyaw4a9lpiiyfne0gjucrn01bv8zt56z.png)
Subtract 2 from both the sides.
![7-2=2+r-2](https://img.qammunity.org/2020/formulas/mathematics/middle-school/pyzrt5uumnmx0huk9ohq0eogs1pnz4guyl.png)
![5=r](https://img.qammunity.org/2020/formulas/mathematics/middle-school/c2pe2m73jovzoao6t5bmhksz9ugwu421s5.png)
Therefore the required equation is 7=2+r and the value of r is 5 units.