Mathematics - Functions Question with Solution | TestHub

$\begin{array}{ll}2x+3y=23& \\ x=1& y=7\\ x=4& y=5\\ x=7& y=3\\ x=10& y=1\\ A& B\\ (1,7)& 1\\ (4,5)& 4\\ (7,3)& 7\\ (10,1)& 10\end{array}$
The number of one-one functions from $A$ to $B$ is equal to 4 !