Iam really struggling with questions 6-10

6a) Find the ratio using the information given on the radii of the cylinders; 
6.3/5.4 = 7/6 ratio

6b) It is stated that the cylinders are similar, using this information write out the information as; 

Let x be the length of the bigger cylinder. 

6.3/5.4=x/10.2 --> we can only write this when we know the shapes are similar

(6.3×10.2)/5.4=x

11.9 cm=x

As you can see, the rest of the question evolve around these to basic key concepts. Try to understand why they work out and how they were found. If you have any questions about how I found the answers, you can ask me. 

Hope I helped :)