Auto change value row on Datagrid

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validation

DataGrid

i have 2 column PRICE and PAYMENT in Datagrid
when i change value of 1 any cell in this Datagrid, other cells also change the value.
Example:
PRICE | PAYMENT
100 | 80 |
20 | 10 |
10 | 5 |

Note:
Row2.cells[0] = row1.cells[0] - row1.cells[1]
similar: row3.cells[0] = row2.cells[0] - row2.cells[1]
Column 1 have value read only. Only column 2 can edit value
Value each row change depends previous line.

when i change value row1.cells[1]= 60, it change below:
row2.cells[0]=40
row2.cells[1] = 40
row3.cells[0] = 0
row3.cells[1] = 0