Given:
Mr. Miller = 280 miles from the house ; rate of 40 mph
Mrs. Miller = rate of 40 mph ; find the distance.
Speed = distance / time
time = distance / speed
time = 280 mi / 40 mph = 280 miles 1h/40mi = 280 h/40 = 7 hours
distance = speed time
distance = 30 mph * 7 hours = 210 miles
Correct answer would be:
A) d = 280 + 40t for Mr. Miller
d = 30t for Mrs. Miller