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If (x + 3) varies directly as y and x = 3 when y = 12, what ...

If (x + 3) varies directly as y and x = 3 when y = 12, what is the value of x when y = 8?

A.

1

B.

12

C.

D.

-1

Correct answer is A

(x+3) \propto y\\ ∴x + 3 = ky\hspace{1mm}when\hspace{1mm}x = 3, y = 12\\ 3+3 = 12k\\ ∴ k = \frac{1}{2}\\ \Longrightarrow x + 3 = \frac{1}{2}y to find x when y = 8
x + 3 = \frac{1}{2}\times 8\\ x=4-3\\ x = 1