I think they will meet in 4 minutes.
Explanation
10+15+15+15+15=70
150-20-20-20-20=70
Every minute the first balloon goes up 15 meters and the second balloon goes down 20 meters.
9 + 10=21 :)
9=3 x3
10= 2 x 5
3x5=15
3x2=6
15 + 6 = 21 :)
Answer:
The Answer Is 74. Your Welcome