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

$A$ function $f$ is defined by $f(x) = 2x - 5$. Find the value of $f(-3)$.

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

The number of relations $R$ from an $m$-element set $A$ to an $n$-element set $B$ satisfying the condition $(a, b_1) \in R, (a, b_2) \in R \Rightarrow b_1 = b_2$ for $a \in A, b_1, b_2 \in B$ is

If $f$ is a relation from the set of positive real numbers to the set of positive real numbers defined by $f(x) = 3x^2 - 2$,then $f$ is

Examine the following relation and state whether it is a function or not,giving reasons: $R = \{(2, 2), (2, 4), (3, 3), (4, 4)\}$