Each Machine of type A has 3 steel parts and 2 chrome parts. Each machine of type B has 2 steel parts and 4 chrome parts. If a certain group of type A and type B machines has a total of 50 steel parts and 66 chrome parts, how many machines are in the group  Options:
A) 11
B) 21
C) 31
D) 61
E) 51

Rationale: "look at the below representation of the problem : steel chrome total a 3 2 50 > > no . of type a machines = 50 / 5 = 10 b 2 4 66 > > no . of type b machines = 66 / 6 = 11 so the answer is 21 i . e b . hope its clear ."
Answer: B