Let the number to be added be x.

$\frac{-3}{4}+x=\frac{5}{16}$

$x=\frac{5}{16}+\frac{3}{4}=\frac{5}{16}+\frac{12}{16}=\frac{17}{16}$.

A number which can be written in the form $\frac{p}{q}$ , where p and q are integers and q ≠ 0 is called a rational number.
By the above definition, $\frac{p}{q}$ can be a rational number only when q ≠ $0$.
So, for the given fraction to be not a rational number, x should be zero.
For all the other given values of x, we will obtain a rational number.
For example, when x = 1,
$\frac{-11}{x}=\frac{-11}{1}=-11$ 
when x = 2,
$\frac{-11}{x}=\frac{-11}{2}=-5.5$ 
when x = -1,
$\frac{-11}{x}=\frac{-11}{-1}=11$ 

By using the number line, we know that the statement is true.

$\frac{44}{22}=\frac{2}{1}$    [Dividing both numerator and denominator by 22]
$\frac{2}{1}=2$

Consider $\frac{2}{3}$.
To make the numerator 8, we have to multiply the numerator by 4.

Therefore, multiplying both numerator and denominator by 4 gives the required number.
$\frac{2\times 4}{3\times 4}=\frac{8}{12}$

Therefore, required rational number is $\frac{8}{12}$.​

Any number which can be represented in the form of $\frac{p}{q}$ where $p$ and $q$ are integers and $q\ne 0$ is a rational number. 

Each part: 1 Mark 
(i) Additive Inverse of $\frac{7}{8}$ will be -$\frac{7}{8}$ since the sum of both is 0.
(ii) Additive Inverse of $\frac{1}{2}$  will be -$\frac{1}{2}$, since their sum will be 0. 

Formula: 1 Mark
Answer: 1 Mark
The circumference is given by the formula $C=2\times \pi \times r$
So, $C=2\times \pi \times 3=6\pi$
The area is given by the formula  $A=\pi \times r^2$
So, $A=\pi \times 3^2=9\times \pi$
As, $\pi$ is irrational, so the circumference and area are both irrational.