I need help on benchmark question

The answer is B. y=x+3

All you needed to do was replace the x with the numbers on “miles sally run (x)” and which ever one matched up with Sally’s then that would’ve been the answer.

For example.
y=(3) + 3 = 6
y=(9) + 3 = 12
and it’s equivalent to the other side aka “mile Keith runs”

y