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 7 Ohms?  Select.
A) 3/5	B) 1/7	C) 12/35	D) 31/12	E) 35/12
1/R = 1/x + 1/y   1/R = 1/5+1/7 = 12/35   R = 35/12   The answer is 35/12.
<result>E</result>
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 7 Ohms?