In an electric circuit, two resistors with resistances x and y are connected in parallel. If R is the combined resistance of these two resistors, then the reciprocal of R is equal to the sum of the reciprocals of x and y. What is R if x is 5 Ohms and y is 6 Ohms?
Options
A) 7 / 30
B) 11 / 30
C) 11 / 15
D) 30 / 11
E) 15 / 11

Rationale: 1 / r = 1 / x + 1 / y 1 / r = 1 / 5 + 1 / 6 = 11 / 30 r = 30 / 11 the answer is d .
Answer: D