In Gabriel's sheep herd, every sheep has either fleas or lice or both. Half of the sheep have lice, and 84 sheep have both pests. If 94 sheep have lice, how many sheep have only fleas?  Choose the correct choice.
A) 10
B) 20
C) 84
D) 94
E) 178

Rationale: n ( lice ) = n ( only lice ) + n ( both lice and fleas ) n ( both lice and fleas ) = 84 n ( lice ) = 94 n ( only lice ) = 94 - 84 = 10 since , it is also said that exactly half the sheep have lice , it can be inferred that half the number of sheep is 94 . therefore , the total number of sheep having only fleas is 10 ans : ( option a )
Answer: A