a ribbon 12/15 m is cut into two parts. If one part is 3/5 m long, then what is the length of other part?

12/15 (m) - 3/5 (m)

find the common denominator = 15

when multiplying the denominator (s), multiply the numerator (s) by the same value.

12/15 (m) - 9/15 (m) = 3/15 (m), simplify to get 1/5 (m), divide both the numerator and denominator by 3