I think the equations are simple enough where plugging in a few values for x and y would be the quickest strategy here.
My general approach with plugging in values is to use 0, positive, and negative values.

If x = 0 and y = 0:
Quantity A = (0)(0) + 2 = 2
Quantity B = (0+7)(0-3) = 7 * -3 = -21
A > B

If x = 1 and y = 4:
Quantity A = (1)(4) + 2 = 6
Quantity B = (1+7)(4-3) = 8 * 1 = 8
A < B

Since there are possible values of x and y that give us multiple relationships between Quantity A and B, the answer is D.