The equation between number of euro and number of dollars will be in the form y = kx.
y is the value in dollars and x is the value in euros.
From the information given,
8 euro = 9 dollar
dividing by '8' we can say:
8/8 euro = 9/8 dollars
1 euro = 9/8 dollar
This is the value for k.
Thus, we have:
[tex]y=\frac{9}{8}x[/tex]We were given 8 euro = 9 dollar and 40 euro = 45 dollars. Let's see if they are correct using our equation:
[tex]\begin{gathered} y=\frac{9}{8}\times8 \\ y=9 \\ \text{Correct!} \\ y=\frac{9}{8}\times40 \\ y=45 \\ \text{Correct!} \end{gathered}[/tex]Thus the correct relationship is:
[tex]y=\frac{9}{8}x[/tex]