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This problem trains for: SAT-I, GMAT, AMC-10.
If a, b, c, d, p, m, n are distinct non-zero digits that satisfy (the letters represent digits for the respective place values):
Then, if g is the number of possible values for a+c and f is the number of possible values for b+d, the value of g/f is:
By adding two digits we cannot get a carry-over larger than 1. Therefore,
Since the digits are distinct, none of a, b, c, d, m, n can be 1.
Since the lowest values possible for b and d are2, 3 and there is no carry-over from their addition:
Similarly, since the lowest value of n is 2: