The answer is the last one
As the time go the grass height go through increasing and decreasing
Answer:
20 miles
Step-by-step explanation:
d miles × (1 h)/(10 miles) = d/10 hours
d miles × (1 h)/(40 miles) = d/40 hours
d/40 = d/10 - 3/2
d = 4d - 60
d = 20 miles
