Question 26019
Let number going originally be "x".
Each must have paid 1800/x
If six dropped out that would be 6(1800/x)
The remaining group numbers "x-6".
EQUATION:
1800-6(1800/x)+(x-6)10=1800
     6(1800/x)=10(x-6)
     10800=10x^2-60x
Divide by 10 to get:
      x^2-6x-1080=0
   (x-36)(x+30)=0
    x=36
There were originally 36 in the group.

Cheers,
Stan H.