In solving these problem I find it helpful to use the following table: 10 rows of digits, N columns for each letter. Put a checkmark in the cell when you know the value of a letter. Put an X in a cell when you know that a letter can't have this value. After putting a checkmark in a cell you can put Xs in all other cells in the same row and column.View attachment 27827
Value of R + P + A + D ? (a) 20 (b) 21 (c) 23 (d) 24
P can be zero or Nine .
No work done till now