The value of \(\left(5 \frac 1 4 \div \frac 3 7 \rm\;of\;\frac 1 2\right) \div \left(5 \frac 1 9 - 7 \frac 7 8 \div 9 \frac 9 {20}\right) \times \frac {11}{21} - \left(5 \div 2 \rm \;of\;\frac 1 2\right)\) is:
1
\(\frac {35}{24}\)
2
0
3
-2
4
\(\frac {15}{28}\)