Answer:
13.8
Step-by-step explanation:
When y varies directly with x, we have the relationship [tex]y=kx[/tex] where [tex]k[/tex] is the constant of proportionality.
To determine [tex]k[/tex], we simply need to determine the slope, or rate of change, using the coordinate points [tex](x_1,y_1)\rightarrow(2,27.60)[/tex] and [tex](x_2,y_2)\rightarrow(6,82.80)[/tex]:
[tex]k=\frac{y_2-y_1}{x_2-x_1}=\frac{82.80-27.60}{6-2}=\frac{55.20}{4}=13.8[/tex]
Therefore, the constant of proportionality is 13.8
