If x, y, z are three numbers such that x + y = 13, y + z = 15 and z + x = 16, then the value of (xy + xz) / (xyz) is:
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Correct answer: B
Explanation
The correct answer is option 2 i.e 5 / 18
⇒ x + y = 13
⇒ y + z = 15
⇒ x + z = 16
By adding three of theorem
⇒2(x + y + z) = 44
⇒ x + y + z = 22
By using all the given equations
⇒ x = 7 & y = 6 & z = 9
⇒ (xy + xz) / (xyz)
⇒ (7 × 6 + 7 × 9) / (7 × 6 × 9)
⇒ (42 + 63) / 378
⇒ 105 / 378
⇒ 5 / 18