If y varies directly as x and y = 49 when x = 7, what is the value of y when x = 3?

Direct variation means y = kx for a constant k. Using y = 49 when x = 7 gives k = 49 ÷ 7 = 7, so when x = 3, y = 7 × 3 = 21. The correct choice is D, 21.

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