Question

please tell me the answer​

Answer 1

Answer:

There are 9 boxes in forth stage

Answer 2

Step-by-step explanation:

first stage : 1 + 0 = 1

second stage : 2 + 1 = 3

third stage : 3 + 2 + 1 = 6

fourth stage : 4 + 3 +2 +1 = 10

fifth stage : 5 + 4 + 3 + 2 + 1 = 15.

And so on.