Step 1
The nth term of an A.P is given as;
[tex]\begin{gathered} a_n=a_1+(n-1)d \\ a_1=7 \end{gathered}[/tex]Step 2
[tex]\begin{gathered} a_2=7+(2-1)d \\ a_2=7+d \\ a_{10}=2(7+d)=14+2d \\ a_{10}=7+9d \\ 7+9d=14+2d \\ 7d=7 \\ d=1 \end{gathered}[/tex]Hence the 8th term will be;
[tex]\begin{gathered} a_8=7+(8-1)d \\ a_8=7+7(1) \\ a_8=14 \end{gathered}[/tex]