To find the corresponding \( y \) value when \( x = 3 \), you can use either of the given equations. Let's plug \( x = 3 \) into each equation to find \( y \).
Starting with Miles' equation:
\[ y = 60 + 20x \]
Substituting \( x = 3 \):
\[ y = 60 + 20(3) \]
\[ y = 60 + 60 \]
\[ y = 120 \]
Now let's check Addison's equation to make sure we get the same \( y \):
\[ y = 90 + 10x \]
Substituting \( x = 3 \):
\[ y = 90 + 10(3) \]
\[ y = 90 + 30 \]
\[ y = 120 \]
So in both equations, when \( x = 3 \), the corresponding \( y \) value is \( 120 \).
Thus, the value of \( y \) when \( x = 3 \) is 120.