The number of terms of an A.P. is even; the sum of all the odd terms is \( 24 \), the sum of all the even terms is \( 30 \) and the last term exceeds the first by \( \frac{21}{2} \). Then the number of terms which are integers in the A.P. is:
\( 4 \)
\( 8 \)
\( 6 \)
\( 10 \)
