If 3(x+y) = 81 and 81(x-y) = 3, then what is the value of x?
2019
If 3(x+y) = 81 and 81(x-y) = 3, then what is the value of x?
- A.
17/16
- B.
17/8
- C.
17/4
- D.
15/4
Attempted by 19 students.
Show answer & explanation
Correct answer: B
Correct answer: 17/8
From 3(x+y) = 81 = 34, we get x + y = 4.
From 81(x-y) = 3 and 81 = 34, we get 34(x-y) = 31, so x - y = 1/4.
Adding the equations gives 2x = 4 + 1/4 = 17/4.
Therefore, x = 17/8.
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