f one plane is flying at 40 mph while another is flying at 100 mph, and they are 200 miles apart and flying directly towards each other, how long will it take them to meet?

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