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: -57
Step-by-step explanation:
15 + ( - 72)
Distribute
15 - 72
When this happens, you subtract the smaller number by the bigger one, then put the sign that was on the bigger number on what you get.
72 - 15 = 57
Put a negative sign on 57
-57
15 + (-72) = -57
Answer/Step-by-step explanation:
a. Using two points on the line (0, 2) and (4, 12), find the gradient:
Gradient = ∆y/∆x = (12 - 2) / (4 - 0) = 10/4 = 2.5
Gradient = 2.5
b. The gradient, 2.5, represents the unit rate. That is, the volume of the oil in the tank per second.
i.e. 2.5 litres per second
c. The value, L = 2 represents the y-intercept, which is the starting value or initial volume of oil in the tank at 0 secs.