Let us pick two random integers say x and y. It is given that 10 of x is y, then what will be $ y\% $ of 80 be:
A. $ 8\% $ of x
B. $ 8\% $ of y
C. 8x
D. 8y

Hint: In this question, we have been given two integers x and y. As given that 10 of x is y, we will write it in equation form and then calculate the $ y\% $ of 80 by putting the value from the obtained equation and get the desired answer,

Complete step by step answer:
We have been given that we have two integers x and y and 10 of x is y.
We have to find the $ y\% $ of 80.
Now as given in the question that 10 of x is y.
We can write the given information in the mathematical form as
 $ \begin{align}
  & \Rightarrow 10\times x=y \\
 & \Rightarrow 10x=y...........(i) \\
\end{align} $
Now, we calculate the $ y\% $ of 80.
In mathematical we can write as
 $ \Rightarrow \dfrac{y}{100}\times 80 $
Now, by putting the value of y from equation (i), we get
 $ \Rightarrow \dfrac{10x}{100}\times 80 $
Now, on simplifying further we get
 $ \Rightarrow 8x $
So, we get $ y\% $ of 80 is 8x.
Option C is the correct answer.

Note:
 We can understand this question by taking the value of two integers. As there is a difference between $ 8\% $ of x and 8x. So, be careful while choosing the option. The percentage of a number is expressed as a fraction of 100. The percentage is denoted by a symbol $ \% $.