Answer:
B: d = 40t
Explanation:
Ian traveled 50 miles, d, in 1 hour, t. This means that for d to be equal to some value of t, you would have the equation d = 50t. If Rachel is slower, that means she doesn't travel as far as Ian does in 1 hour. This means that whatever value you multiply t by in Rachel's equation, it must be less than 50, and the only answer choice with less than 50 is 40, meaning B is the answer. I hope this made sense and I could be of some help!