(ax+b)=(cx+d)
ax-cx=d-b
x(a-c)=d-b
x=(d-b)/(a-c)
So if a,b,c,d are integers then the subtraction and division of integers must also be rational. Is that the answer?
Suppose a,b,c,d are integers and a DOES NOT equal c. Suppose that x is a real number that satisfies the equation:
(ax+b)/(cx+d)=1
Must x be rational? If so, express x as a ratio of two integers.
I have no idea how to begin this problem.