I need help on this issue!
Consider the following data relating to a series of three experiments involving a particular
reaction.
Be the equation: A + B----------> C + D
1st Experience: ma     mb    mc    7,0g
2nd Experience: m'a   24,0g  12,0g md
3rd Experience: 30,0g  m''b   m''c  50,0g
In the third experience was of D. 50,0g The formation of D mass obtained in Experiment 2 equals
A) 15.0g.
B) 3.0 g. D) 35,0g.
C) 45,0g. E) 30,0g.

Are you sure you have given all informations related with this experiments.Can you send me more details of the experiments

Not "dm" but "md".

some information is missing

May be it is in college syllabus.