which is similar to n:1 where 
<u>Step-by-step explanation:</u>
Here we have to Express in the form n:1 give n as a decimal 21:12 . Let's find out:
Given ratio as 21:12 . Let's convert it into n:1 , where n is decimal
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{ dividing denominator & numerator by 4 }
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which is similar to n:1 where 
Answer:
im sorry i don't know the answer i just need to do this so that i can ask my question pls forgive me
Omg I have the same page as you. But here’s the first one for number 19
Answer:

Step-by-step explanation:
Total Surface Area of Cylinder = 
Given from the question, r = 7 cm and h = 15cm
Lets Substitute r and h into the formula to find the Total Surface Area of the cylinder.
Total Surface Area of Cylinder = 
(7+y)+z
Step-by-step explanation:
this is to separate the sum of 7 and y from z