Answer:
All are valid
Explanation:
Px - 43 = -42x + Q (rearrange)
x = (Q+43) / (P + 42) <----Substitute options for P & Q into this equation to see which combination gives exactly 1 solution for x
A) P=42, Q = 42; x = (42+43) / (42+42) = 1.011 (only 1 solution = valid)
B) P=43, Q = -42; x = (-42+43) / (43+42) = 0.012 (only 1 solution = valid)
C) P=-43, Q = -43; x = (-43+43) / (-43+42) = 0 (only 1 solution = valid)
D) P=42, Q = 43; x = (42+43) / (42+42) = 1.023 (only 1 solution = valid)