There are 72 marbles in the two bags, (a) and (b). If there are 42 marbles in sack (A), how many more marbles are in sack (A) than in sack (B)?
42 72 42 [OP_SUB] [OP_SUB]
var_a = 42
var_b = 72
var_c = 42
var_d = var_b - var_c
var_e = var_a - var_d
print(int(var_e))