Answer:
Pat a) The unit rate of graph at left is
![25\ (grams)/(cup)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/s5gwr4ih8pooibdzt1o7hqd8gvsuyegdtk.png)
Part b) The unit rate of graph at right is
![40\ (grams)/(cup)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/iutmh0n46ozjjpinsc9q0rj1pue3nbz4zm.png)
see the attached figure
Explanation:
we know that
The unit rate of a linear equation is the same that the slope of the linear equation
step 1
Find the slope of the graph at left
This graph represent a proportional relationship (because the line passes through the origin)
The slope is equal to the constant of proportionality k
![k=(y)/(x)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/k3udmoohkeqhw599yc73nqw67cmif8a8rn.png)
we have the point (1,25)
substitute the values in the formula
![k=(25)/(1)=25\ (grams)/(cup)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/zohhq4h59ayczldxk709l820m7xttwx94o.png)
step 2
Find the slope of the graph at right
we have the points (2,80) and (3,120)
This graph represent a proportional relationship (because the line passes through the origin)
The slope is equal to the constant of proportionality k
![k=(y)/(x)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/k3udmoohkeqhw599yc73nqw67cmif8a8rn.png)
Is necessary only one point to determine the constant of proportionality
take the point (2,80)
substitute the values
![k=(80)/(2)=40\ (grams)/(cup)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/jqc4d84qj4sgqm3ahfvnmayw85pthtuj9w.png)
Verify
The formula to calculate the slope between two points is equal to
![m=(y2-y1)/(x2-x1)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/3alxf865ejd0fdnwnbs21cssprdlquqoeh.png)
we have the points (2,80) and (3,120)
substitute the values
![m=(120-80)/(3-2)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/f1pnpyu1gfkl0vnyisn0pw526rt7dru16j.png)
![m=(140)/(1)=40\ (grams)/(cup)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/bnzw2nqt03j5oa36w7waefz2ldf89b7it8.png)