Question

Solve for x: 2/5=4/x

Answer 1

The answer is 10


Explanation: First you cross-multiply to get 2x=20 and then divide by 2 to get x=10

Answer 2

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Answer:

  x = 10

Step-by-step explanation:

Using your number sense, you recognize that a fraction equivalent to 2/5 that has 4 in the numerator is 4/10. This tells you x = 10.

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The usual instructions for solving this algebraically are to "cross multiply", then divide by the coefficient of x.

  2/5 = 4/x . . . . given

  2x = 20 . . . . . multiply by 5x on both sides

  x = 10 . . . . . . . divide by 2

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You can do the above two steps both at once: multiply by 5/2x.

  (2/5)(5/2x) = (4/x)(5/2x)

  x = 20/2 = 10