Answer:
420 miles
Step-by-step explanation:
Distance = rate × time
Let's say that the distance is D and that John's speed is S. We know that:
D = S × 6
When Elliot drives at speed S+14:
D = (S+14) × 5
Setting D = D:
S × 6 = (S+14) × 5
6S = 5S + 70
S = 70
Therefore, the distance D is:
D = 70 × 6
D = 420
The distance from John's house to Miami is 420 miles.