Answer: 20 pieces of chocolate could be treated for 35 pieces of hard candy.
Step-by-step explanation:
Equation of direct proportion between two quantities x and y :
[tex]\dfrac{x_1}{y_1}=\dfrac{x_2}{y_2}[/tex]
Put [tex]x_1=4,\ y_1=7,\ y_2=35, x_2=x[/tex]
[tex]\dfrac{4}{7}=\dfrac{x}{35}\\\\\Rightarrow\ x=\dfrac{35\times4}{7}\\\\\Rightarrow\ x=20[/tex]
Hence, 20 pieces of chocolate could be treated for 35 pieces of hard candy.
