A particular shade of purple paint requires 5 parts blue to 3 parts red paint. If you have 1 gallon of red paint, how many gallons of blue paint are needed to create the same shade of purple?

Answer 1

^{5 blue} / _{3 red} * 1 red

Reds cancel out:

^{5 blue} / ₃ * 1

Anything times 1 is itself:

^{5 blue} / ₃, or ⁵/₃ gallons of blue paint