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If x =2/3y and y = 18, what is the value...

If `x =2/3`y and y = 18, what is the value of 2x − 3 ?

A

21

B

15

C

12

D

10

Text Solution

Verified by Experts

The correct Answer is:
A
Substituting the given value of y = 18 into the equation `x=2/3y` yields `x=(2/3)(18)`, or x=12 . The value of the expression 2x − 3 when x = 12 is 2(12) − 3 = 21.
Choice B is incorrect. If 2x − 3 = 15, then adding 3 to both sides of the equation and then dividing both sides of the equation by 2 yields x = 9. Substituting 9 for x and 18 for y into the equation `x=2/3y` yields `9=2/3 18=12` , which is false. Therefore, the value of 2x − 3 cannot be 15.
Choices C and D are also incorrect. As with choice B, assuming the value of 2x – 3 is 12 or 10 will lead to a false statement.
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