The function $t$,which maps temperature in degree Celsius into temperature in degree Fahrenheit,is defined by $t(C) = \frac{9C}{5} + 32$. Find the value of $C$ when $t(C) = 212$.

$A$ function $f$ is defined by $f(x) = 2x - 5$. Find the value of $f(7)$.

Which of the following relations are functions? Give reasons. If it is a function,determine its domain and range.
$\{(2,1), (5,1), (8,1), (11,1), (14,1), (17,1)\}$

The function $t$ which maps temperature in degree Celsius into temperature in degree Fahrenheit is defined by $t(C) = \frac{9C}{5} + 32$. Find $t(-10)$.

Statement $1$ : If $A$ and $B$ are two sets having $p$ and $q$ elements respectively,where $q > p$. Then the total number of functions from set $A$ to set $B$ is $q^p$.
Statement $2$ : The total number of selections of $p$ different objects out of $q$ objects is ${}^qC_p$.

Let $N$ be the set of natural numbers and the relation $R$ be defined on $N$ such that $R = \{(x, y) : y = 2x, x, y \in N \}$. What is the domain,codomain,and range of $R$? Is this relation a function?