A.) 2.5x+3y=12
B.) -10x-3y=1
C.) 2x+3y=12
D.) 5x+5y=10
Standard Form: the standard form of a line is in the form Ax + By = C where A is a positive integer, and B, and C are integers.
This eliminates A.... (2.5 isn't an integer) and B...("A" in the equation is negative).
C and D are correct.