Pheobe has 9 rocks. she puts the rocks into 3 boxes. each box 1 more rock then the last. how many rocks are in each box

Hello!

We can write this as the system of equations below. We have boxes A, B, and C.

A+B+C=9
B=A+1
C=B+1

First of all we can plug our B and C values into the first equation and solve for A.

A+A+1+A+1+1=9
3a+3=9
3a=6
a=2

Now we can plug our a value into the other equations.

B=2+1
B=3

C=3+1
C=4

Therefore, there are 2 rocks in one box, three in another, and 4 in the last.

I hope this helps!