Answer :
The slope of a line is given by:
[tex]m=\frac{y_2-y_1}{x_2-x_1}[/tex]Plugging the values of the problem we have:
[tex]3=\frac{19-10}{x-4}[/tex]Solving for x we have:
[tex]\begin{gathered} 3=\frac{19-10}{x-4} \\ 3=\frac{9}{x-4} \\ 3(x-4)=9 \\ x-4=\frac{9}{3} \\ x-4=3 \\ x=3+4 \\ x=7 \end{gathered}[/tex]Therefore, x=7.