Isaac cut his 30 meters ribbon into 6 equal parts. He then used 4 parts of the ribbon. How many meters of ribbon are not used? Let's answer step by step:
Each part is 30 / 6 = 5 meters long. Since Liam used 4 parts, then he used 5 x 4 = 20 meters of the ribbon. So, 30 - 20 = 10 meters of ribbon is not used. The answer: 10.