Answer:
t = 1 3/7 hours
Step-by-step explanation:
For plane 1
distance = rate *t
d1 = 40 *t
For plane 2
distance = rate * time
d2 = 100 * t
We know that d1+d2 = 200 (the planes will meet)
We know that the times will be the same because the leave at the same time.
Substitute in d1 =40t and d2 = 100t into d1+d2 = 200
d1+d2 = 200
40t + 100t = 200
Combine like terms
140t = 200
Divide each side by 140
140t/140 = 200/140
t= 200/140
t= 20/14
t = 10/7
t = 1 3/7 hours
