Let R be the length of the red ribon and let I be the length of the indigo ribbon. We have that the red ribbon is 6 1/4 inches long, then:
[tex]R=6\frac{1}{4}=\frac{25}{4}[/tex]Then, the indigo ribbon is 6 1/4 inches longer than the red ribbon. Then we have:
[tex]I=R+6\frac{1}{4}[/tex]therefore:
[tex]I=\frac{25}{4}+\frac{25}{4}=\frac{50}{4}=\frac{25}{2}=12\frac{1}{2}[/tex]finally, we have that the indigo ribbon is 12 1/2 inches long
