What is the value of y in the equation 6.4x + 2.8y = 44.4, when x = 3?

Substitute x = 3 into the equation: 6.4(3) + 2.8y = 44.4. This gives 19.2 + 2.8y = 44.4, so 2.8y = 25.2. Dividing by 2.8 gives y = 9, so the correct choice is y = 9.

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