For the following two (02) items:
Let $\cos (2x+3y)=\frac{1}{2}$ and $\cos (3x+2y)=\frac{\sqrt{3}}{2}$  where  $-\pi <(2x+3y)<\pi $ and $-\pi <(3x+2y)<\pi .$

How many values does (y-x) have?

For the following two (02) items:
Consider the equation abx² + bcx + ca = cax² + abx + bc

If the roots of the equation are equal, then which one of the following is correct?

For the following two (02) items:
Consider the equation abx² + bcx + ca = cax² + abx + bc

If the roots of the equation are equal, then a, b, c are in

For the following two (02) items:
Let ( 6 + 10 + 14 +... up to m terms) =( 1 + 3 + 5 + 7 +... up to n terms)
where m < 25 and n < 25

What is the relation between m and n?